Fix typo

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Closes #1678

Differential Revision: D7214596

fbshipit-source-id: 3224ed09c2d8992d41ac199a6e2f1320462df59a

Author: purezen

docs/APIReference-EditorState.md

@@ -358,7 +358,7 @@ as the set of inline styles to be applied to the next inserted characters.
 ```
 static set(editorState: EditorState, options: EditorStateRecordType): EditorState
 ```
-Returns a new `EditorState` object with new options passed in. 'The method is
+Returns a new `EditorState` object with new options passed in. The method is
 inherited from the Immutable `record` API.
 
 ## Properties and Getters