Document the new features in Notebook 7

[jtpio]

Before the first 7.0 beta is released, we should document some of the major new features available in Notebook 7.

Taking inspiration from https://jupyter.org/enhancement-proposals/79-notebook-v7/notebook-v7.html, but with screenshots or videos.

The documentation should also cover how to configure extensions, toolbars and other components. A concrete example would be to explain how to enable the file search bar in the file browser toolbar (added in #6757).

[AnkurRajneta]

I have created an outline regarding the documentation .In which file do I need to make changes @jtpio

[jtpio]

Thanks @AnkurRajneta.

Maybe it could be in the user documentation for now: https://jupyter-notebook.readthedocs.io/en/latest/user-documentation.html. We can always restructure the docs later.

[AnkurRajneta]

Unable to find the repository .Can you point me the location @jtpio

[jtpio]

Closing as fixed by #6813.

Docs: https://jupyter-notebook.readthedocs.io/en/latest/notebook_7_features.html