[update] docs for v9.1

Author: mafanya23

docs/assets/grid/multisort_grouped_data.png

@@ -8,16 +8,12 @@ description: You can explore the getSortingStates method of DataCollection in th
 
 @short: returns an array of objects with the current parameters of sorting applied to the data
 
-:::note
-The method allows getting the result of sorting data by multiple columns.
-:::
-
 ## Usage
 
 ~~~jsx 
 interface ISortingState {
-    by?: string | number, 
-    dir?: "asc" | "desc", 
+    by: string | number, 
+    dir: "asc" | "desc", 
     as?: (a) => any,
     rule?: (a, b) => number, 
     smartSorting?: boolean 
@@ -48,15 +44,15 @@ The array returned by the method contains objects with the following properties:
         </tr>
         <tr>
             <td><b>as</b></td>
-            <td>(<i>function</i>) a custom function of converting values before comparing</td>
+            <td>(<i>function</i>) optional, a custom function of converting values before comparing</td>
         </tr>
         <tr>
             <td><b>rule</b></td>
-            <td>(<i>function</i>) a custom sorting function</td>
+            <td>(<i>function</i>) optional, a custom sorting function</td>
         </tr>
         <tr>
             <td><b>smartSorting</b></td>
-            <td>(<i>boolean</i>) (if applied) specifies whether a sorting rule should be applied each time after changing the data set</td>
+            <td>(<i>boolean</i>) optional, (if applied) specifies whether a sorting rule should be applied each time after changing the data set</td>
         </tr>
     </tbody>
 </table>

docs/assets/grid/multisorting_data.png

@@ -345,21 +345,13 @@ grid.data.sort({
 The described functionality requires PRO version of the DHTMLX Grid (or DHTMLX Suite) package.
 :::
 
-You can sort Grid by multiple columns simultaneously. The multi-sorting ability is enabled by default. If you need to disable it, set the [`multiSort`](grid/api/grid_multisort_config.md) Grid property to *false*.
+You can sort Grid by multiple columns simultaneously. 
 
-~~~jsx
-const grid = new dhx.Grid("grid_container", {
-    columns: [
-        // columns config
-    ],
-    multiSort: false,
-    data: dataset
-});
-~~~
+![](../assets/grid/multisorting_data.png)
 
 **Related sample**: [Grid. Sorting by multiple columns (multisorting)](https://snippet.dhtmlx.com/4ej0i3qi)
 
-It is also possible to apply multi-sorting to [the grouped data](grid/usage.md#grouping-data). Check the example below:
+Multi-sorting is enabled on initialization of the component. In the example below Grid data is sorted with the help of the `sort()` method of [DataCollection](data_collection.md) by several columns:
 
 ~~~jsx
 const grid = new dhx.Grid("grid_container", {
@@ -379,8 +371,22 @@ grid.data.sort({ by: "task_status", dir: "asc" });
 grid.data.sort({ by: "animal_type", dir: "asc" });
 ~~~
 
+![](../assets/grid/multisort_grouped_data.png)
+
 **Related sample**: [Grid. Grouping with sorting by multiple columns (multisorting)](https://snippet.dhtmlx.com/786zr190)
 
+If you need to disable the multi-sorting ability, set the [`multiSort`](grid/api/grid_multisort_config.md) Grid property to *false*.
+
+~~~jsx
+const grid = new dhx.Grid("grid_container", {
+    columns: [
+        // columns config
+    ],
+    multiSort: false,
+    data: dataset
+});
+~~~
+
 #### Custom sorting
 
 You can also specify the `rule` attribute in a passed object instead of the default ones and set a custom function for sorting. For example:

docs/data_collection/api/datacollection_getsortingstates_method.md

@@ -8,27 +8,25 @@ description: You can explore how to connect DHTMLX Suite to a backend. Browse de
 
 ![](../assets/integration/work_with_backend.png)
 
-DHTMLX Suite 9 or DHTMLX components don't have any special requirements for the backend. They can be easily connected with any backend platform which supports the REST API (RESTful API).
+DHTMLX Suite 9 or DHTMLX components don't have any special requirements for the backend. They can be easily connected with any backend platform which supports the REST API (RESTful API). Besides, the DHTMLX library allows providing a [multi-user backend](#multiuser-real-time-updated-backend-save-method-getting-editing-deleting-and-sending-data) for any Suite component.
 
-The DHTMLX library includes the [DataCollection](/data_collection/) helper that completely supports REST API for dealing with the backend.
+The DHTMLX library includes the [DataCollection](/data_collection/) helper that completely supports REST API for dealing with the backend. Thus, to transfer data from your backend to the Suite components, all you need to do is create a valid JSON dataset. You can load it into the component using the [load()](/data_collection/api/datacollection_load_method/) method of DataCollection.
 
-Thus, to transfer data from your backend to the Suite components, all you need to do is create a valid JSON dataset. You can load it into the component using the [load()](/data_collection/api/datacollection_load_method/) method of DataCollection.
 
-Besides, the DHTMLX library allows providing a [multi-user backend](#multi-user-backend-for-suite-widgets) for any Suite component.   
 
 ## Examples of using DHTMLX Suite widgets with Node.js
 
-Let's have an overview of the examples.
-
 :::info
 Download and take a look at the [Examples of using DHTMLX Suite widgets with Node.js](https://github.com/DHTMLX/nodejs-suite-demo).
 :::
 
-Here you can find 11 interactive samples. Follow the instructions in the README.md file to run the examples.
+Here you can find 12 interactive samples. Follow the instructions in the README.md file to run the examples.
 
 You can easily modify any widget for your purposes and find out how it works.
 
+:::tip note
 Pay attention: the components of the demo work with one database. When editing data in one component, you affect data in other components.
+:::
 
 To reset the database, stop the server and delete the file with the `.sqlite` extension from the root directory of the project.
 
@@ -124,17 +122,17 @@ The following request methods are used in this example: `GET`, `PUT`, `POST`, `D
 
 ![](../assets/integration/work_with_backend_save.png)
 
-The example is created to show you how to save the changes made in data to the backend via the **save()** method of DataCollection. 
+The example is created to show you how to save the changes made in data to the backend via the `save()` method of DataCollection. 
 
 This example of Grid is visually the same as the previous one but the ways of adding and editing data in this example are developed in another way. For instance, after you click the "Add new card" button, an empty row will be added after the last row in the grid. Editing of any cell of the grid is implemented by double-clicking on the cell. 
 
 The following request methods are used in this example: `GET`, `PUT`, `POST`, `DELETE`.
 
-## Multi-user backend for Suite widgets
+### Multiuser (real-time updated) backend. Save method. Getting, editing, deleting, and sending data
 
-You can create a multi-user (real-time updated) backend for Suite widgets. The backend can be implemented in any language and you can use any library to allow the client and the server sides interact via the WebSocket protocol.
+This example shows how to implement a multi-user backend for Grid with the help of Node.js and the Faye library to provide live data updates.
 
-There is an [example](https://github.com/DHTMLX/nodejs-suite-demo/blob/master/public/views/12_grid_with_form_multiuser.html) that shows a multi-user backend for Grid, implemented with the help of Node.js and the Faye library. You can provide live data updates for any Suite widget based on this example.
+You can create a multi-user (real-time updated) backend for any Suite widget. The backend can be implemented in any language, and you can use any library that will allow the client and the server sides interact via the WebSocket protocol.
 
 :::info
 Download and take a look at the [Examples of using DHTMLX Suite widgets with Node.js](https://github.com/DHTMLX/nodejs-suite-demo).

docs/grid/usage.md

@@ -8,16 +8,12 @@ description: You can explore the getSortingStates method of TreeCollection in th
 
 @short: returns an array of objects with the current parameters of sorting applied to the data
 
-:::note
-The method allows getting the result of sorting data by multiple columns.
-:::
-
 ## Usage
 
 ~~~jsx 
 interface ISortingState {
-    by?: string | number, 
-    dir?: "asc" | "desc", 
+    by: string | number, 
+    dir: "asc" | "desc", 
     as?: (a) => any, 
     rule?: (a, b) => number, 
     smartSorting?: boolean 
@@ -39,23 +35,23 @@ The array returned by the method contains objects with the following properties:
     <tbody>
         <tr>
             <td><b>by</b></td>
-            <td>(<i>string | number</i>) the id of a data field (a column of Grid) to sort by</td>
+            <td>(<i>string | number</i>) the id of a data field to sort by</td>
         </tr>
         <tr>
             <td><b>dir</b></td>
             <td>(<i>string</i>) the direction of sorting: "asc" or "desc"</td>
         </tr>
         <tr>
             <td><b>as</b></td>
-            <td>(<i>function</i>) a custom function of converting values before comparing</td>
+            <td>(<i>function</i>) optional, a custom function of converting values before comparing</td>
         </tr>
         <tr>
             <td><b>rule</b></td>
-            <td>(<i>function</i>) a custom sorting function</td>
+            <td>(<i>function</i>) optional, a custom sorting function</td>
         </tr>
         <tr>
             <td><b>smartSorting</b></td>
-            <td>(<i>boolean</i>) (if applied) specifies whether a sorting rule should be applied each time after changing the data set</td>
+            <td>(<i>boolean</i>) optional, (if applied) specifies whether a sorting rule should be applied each time after changing the data set</td>
         </tr>
     </tbody>
 </table>

docs/integration/suite_and_backend.md

@@ -20,24 +20,21 @@ This version brings some updates in the API methods. Check the [Migration](migra
 
 ### New functionality
 
-#### Common features
-
-- [Multi-user (live update) backend](integration/suite_and_backend.md#multi-user-backend-for-suite-widgets) for Suite widgets
-
 #### Grid 
 
 - [Row expander](grid/configuration.md#row-expander) with the possibility to insert any Suite widget or HTML content (PRO version)
 - [Multi-sorting](grid/usage.md#sorting-by-multiple-columns) functionality that allows sorting Grid by several columns (PRO version)
 
 ### Fixes
 
-- DataCollection. The `sort()` method called without arguments doesn't reset the applied sorting 
+- DataCollection/TreeCollection. The `sort()` method called without arguments doesn't reset the applied sorting 
 - Grid. Falsy firing of data events on row drag-n-drop
 - Toolbar. Menu wrong item positioning
 - TreeCollection. The `restoreOrder()` method doesn't reset the applied sorting
 
 ### New samples
 
+- [Multiuser (real-time updated) backend. Save method. Getting, editing, deleting, and sending data](https://github.com/DHTMLX/nodejs-suite-demo/blob/master/public/views/12_grid_with_form_multiuser.html)
 - [Grid. Grouping and template in group headers](https://snippet.dhtmlx.com/dywmb6ec)
 - [Grid. Search and highlight results](https://snippet.dhtmlx.com/p74701lu) 
 - [Grid. Hiding columns using header context menu](https://snippet.dhtmlx.com/ygfj3uo3)
@@ -2279,7 +2276,7 @@ Released on January 28, 2020
 - The possibility [to set selection to multiple cells/rows of Grid](grid/usage.md#using-selection-api) via the `setCell()` method of the selection object
 - New additional arrow keyboard shortcuts are added to [Keyboard navigation](grid/configuration.md#keyboard-navigation)
 - The ability [to sort content of any Grid column by clicking on its header](grid/configuration.md#sortable-columns) via the [](grid/api/grid_sortable_config.md) property
-- The [](grid/api/grid_getsortingstate_method.md) method that [allows getting the current state of sorting data in Grid](grid/usage.md#getting-the-sorting-state) is added
+- The `getSortingState()` method that [allows getting the current state of sorting data in Grid](grid/usage.md#getting-the-sorting-state) is added
 - The possibility [to check visibility of a column](grid/usage.md#checking-visibility-of-a-column) via the [](grid/api/grid_iscolumnhidden_method.md) method
 - The ability to enable [dynamic loading of data in Grid](grid/data_loading.md#dynamic-loading)
 - The [](grid/api/grid_afterkeydown_event.md) and [](grid/api/grid_beforekeydown_event.md) events are added