Updates to docs

docs/documents.md

@@ -2,9 +2,9 @@
 
 JupyterLab can be extended in two ways via:
 
-- application plugins (top level): Application plugins extend the
+- Extensions (top level): Application extensions extend the
   functionality of JupyterLab itself, and we cover them in the
-  [Extensions](extensions_dev.md) developer tutorial focuses.
+  [Extensions](extensions_dev.md) developer tutorial.
 - **document widget extensions (lower level):** Document widget extensions extend
   the functionality of document widgets added to the application, and we cover
   them in this section.

docs/extensions_dev.md

@@ -39,8 +39,6 @@ The default plugins in the JupyterLab application include:
 - [Console](https://github.com/jupyterlab/jupyterlab/blob/master/packages/console-extension/src/index.ts) - Adds the ability to launch Jupyter Console instances for
 interactive kernel console sessions.
 - [Services](https://github.com/jupyterlab/jupyterlab/blob/master/packages/services-extension/src/index.ts) - An application-specific interface to `@jupyterlab/services`.
-- [RenderMime](https://github.com/jupyterlab/jupyterlab/blob/master/packages/rendermime/src) - The registry for adding kernel `display_data` renderers.
-- [Document Registry](https://github.com/jupyterlab/jupyterlab/tree/master/packages/docregistry/src) - Used to add functionality around widgets backed by files.
 
 ## Application Object
 The JupyterLab Application object is given to each plugin in