docs(common): main container docs

Author: marin-bratanov

_contentTemplates/common/get-started.md

@@ -143,3 +143,28 @@ To setup a local NuGet package source, so you can install the Telerik components
 1. On the loaded page choose from your purchased products or trial downloads **Progress® Telerik® UI for Blazor**, and click on it.
 #end
 
+
+#telerik-main-container-text
+Open the main layout file (by default, the `~/Shared/MainLayout.razor` file in the Blazor project) and add a `<TelerikRootComponent>` element at its root level. The layout file should look similar to this (there may be additional elements in your app):
+#end
+
+
+#telerik-main-container-snippet
+
+        @inherits LayoutComponentBase
+        
+        @using Telerik.Blazor.Components.RootComponent
+        
+        <TelerikRootComponent>
+        
+            <div class="sidebar">
+                <NavMenu />
+            </div>
+            
+            <div class="main">
+                @Body
+            </div>
+        
+        </TelerikRootComponent>
+#end
+

getting-started/client-blazor.md

@@ -72,6 +72,13 @@ For client-side Blazor, we recommend the usage of `Blazor (ASP.NET Hosted)` proj
                  //more code may be present here
              }
          }
+         
+1. @[template](/_contentTemplates/common/get-started.md#telerik-main-container-text)
+
+    **MainLayout.razor**
+    
+        @[template](/_contentTemplates/common/get-started.md#telerik-main-container-snippet)
+
 
 1. @[template](/_contentTemplates/common/issues-and-warnings.md#mono-linker-issue)
 

getting-started/server-blazor.md

@@ -72,6 +72,12 @@ To use Blazor server-side, you need to use the `Razor Components` type of projec
             }
         }
 
+1. @[template](/_contentTemplates/common/get-started.md#telerik-main-container-text)
+
+    **MainLayout.razor**
+    
+        @[template](/_contentTemplates/common/get-started.md#telerik-main-container-snippet)
+
 
 
 Now your project can use the Telerik UI for Blazor components.

getting-started/what-you-need.md

@@ -117,6 +117,13 @@ namespace MyBlazorAppName
 }
 ````
 
+To allow working with detached popups (for example, dropdown lists, menus, grid filters, etc.), a Telerik-specific Blazor component is needed at the root level of the DOM.
+@[template](/_contentTemplates/common/get-started.md#telerik-main-container-text)
+
+````CSHTML
+@[template](/_contentTemplates/common/get-started.md#telerik-main-container-snippet)
+````
+
 ### Client-side Project Considerations
 
 If you are using a **client-side Blazor** project,