Rename DraftEditorBlock to EditorBlock (#2002)

Summary:
**Summary**

The `DraftEditorBlock` component is exposed to the public API as `EditorBlock`, while the [documentation](https://draftjs.org/docs/advanced-topics-block-components) still mentions `DraftEditorBlock`.
https://github.com/facebook/draft-js/blob/b4183b1519edcd075325adae0cb208551dc80f50/src/Draft.js#L45
Pull Request resolved: #2002

Differential Revision: D15239547

Pulled By: claudiopro

fbshipit-source-id: 43556827d1bc571e98b528562c88038f195534c7

Author: umanghome

docs/Advanced-Topics-Block-Components.md

@@ -58,7 +58,7 @@ class EditorWithMedia extends React.Component {
 ```
 
 If no custom renderer object is returned by the `blockRendererFn` function,
-`Editor` will render the default `DraftEditorBlock` text block component.
+`Editor` will render the default `EditorBlock` text block component.
 
 The `component` property defines the component to be used, while the optional
 `props` object includes props that will be passed through to the rendered
@@ -70,7 +70,7 @@ It is strongly recommended that you use `editable: false` if your custom
 component will not contain text.
 
 If your component contains text as provided by your `ContentState`, your custom
-component should compose a `DraftEditorBlock` component. This will allow the
+component should compose an `EditorBlock` component. This will allow the
 Draft framework to properly maintain cursor behavior within your contents.
 
 By defining this function within the context of a higher-level component,