update docs

docs/designers-developers/developers/data/data-core-block-editor.md

@@ -347,6 +347,21 @@ _Returns_
 
 -   `Array<Editor.InserterItem>`: Items that appear in inserter.
 
+<a name="getInsertionIndex" href="#getInsertionIndex">#</a> **getInsertionIndex**
+
+Determines whether there is only one item that may be inserted.
+
+_Parameters_
+
+-   _state_ `Object`: Editor state.
+-   _clientId_ `?string`: Block client ID.
+-   _destinationRootClientId_ `?string`: Root client ID of block list.
+-   _isAppender_ `boolean`: Determines if the block is added to a set of existing blocks in a list.
+
+_Returns_
+
+-   `number`: The insertion index.
+
 <a name="getLastMultiSelectedBlockClientId" href="#getLastMultiSelectedBlockClientId">#</a> **getLastMultiSelectedBlockClientId**
 
 Returns the client ID of the last block in the multi-selection set, or null
@@ -439,6 +454,19 @@ _Returns_
 
 -   `?string`: Adjacent block's client ID, or null if none exists.
 
+<a name="getOneAllowedItem" href="#getOneAllowedItem">#</a> **getOneAllowedItem**
+
+Determines whether there is only one item that may be inserted.
+
+_Parameters_
+
+-   _state_ `Object`: Editor state.
+-   _rootClientId_ `?string`: Optional root client ID of block list.
+
+_Returns_
+
+-   `string`: The name of the allowed block.
+
 <a name="getPreviousBlockClientId" href="#getPreviousBlockClientId">#</a> **getPreviousBlockClientId**
 
 Returns the previous block's client ID from the given reference start ID.
@@ -605,6 +633,19 @@ _Returns_
 
 -   `boolean`: Whether multi-selection has been made.
 
+<a name="hasOneAllowedItem" href="#hasOneAllowedItem">#</a> **hasOneAllowedItem**
+
+Determines whether there is only one item that may be inserted.
+
+_Parameters_
+
+-   _state_ `Object`: Editor state.
+-   _rootClientId_ `?string`: Optional root client ID of block list.
+
+_Returns_
+
+-   `boolean`: True if there is one item available, false if zero or more than one.
+
 <a name="hasSelectedBlock" href="#hasSelectedBlock">#</a> **hasSelectedBlock**
 
 Returns true if there is a single selected block, or false otherwise.