Added comments to with-history and with-react to help fix TypeScript errors

packages/slate-history/src/with-history.ts

@@ -5,6 +5,11 @@ import { HistoryEditor } from './history-editor'
 /**
  * The `withHistory` plugin keeps track of the operation history of a Slate
  * editor as operations are applied to it, using undo and redo stacks.
+ * 
+ * If you are using TypeScript, you must extend Slate's CustomTypes to use
+ * this plugin.
+ * 
+ * See https://docs.slatejs.org/concepts/11-typescript to learn how.
  */
 
 export const withHistory = <T extends Editor>(editor: T) => {

packages/slate-react/src/plugin/with-react.ts

@@ -8,6 +8,11 @@ import { isDOMText, getPlainText } from '../utils/dom'
 
 /**
  * `withReact` adds React and DOM specific behaviors to the editor.
+ * 
+ * If you are using TypeScript, you must extend Slate's CustomTypes to use
+ * this plugin.
+ * 
+ * See https://docs.slatejs.org/concepts/11-typescript to learn how.
  */
 
 export const withReact = <T extends Editor>(editor: T) => {