Update README with context type descriptions

Added sections for various context types in the README.

Author: jacksorjacksor

16/umbraco-cms/customizing/foundation/contexts/README.md

@@ -13,3 +13,33 @@ Below you can find some articles on how you can work with different contexts:
 ## [Property Dataset Context](property-dataset-context.md)
 
 A Dataset Context is the connection point between a Property Editor and a Workspace and covers a set of properties.
+
+## Current User Context
+
+## Section Context
+
+## Workspace Context
+
+## Property Context
+
+ The data regarding the specific property
+
+## Modal Context
+
+Available for a Modal, read the parsed data, submit/close and send a value back
+
+## Entity Context
+
+Holds simple-dataset on the Entity, available for Tree Items or Picked Items, so when not in a Workspace this is where you get some information.
+
+## App Language Context
+
+Knowledge on the Culture of the Application, the dropdown in the top of the Content-Section Sidebar
+
+## Workspace Split View Context
+
+Relevant when working with Split View.
+
+## Block Entry Context
+
+Holds the data for a Block, this is available for Block Custom Views. Notice Block Custom View Elements does get most information via Properties assigned, but if you like to do some editing or advanced stuff then this is available.