Ablog

Merged

https://github.com/sunpy/ablog/pull/86
https://github.com/sunpy/ablog/pull/87
https://github.com/sunpy/ablog/pull/88
https://github.com/sunpy/ablog/pull/89

Many thanks to everyone who contributed.

Fixed rss Feed ID.

See https://ablog.readthedocs.io/release/ablog-v0.10-released/#ablog-v0-10-11-released

See https://ablog.readthedocs.io/release/ablog-v0.10-released/#ablog-v0-10-10-released

Added new way to create blog posts from https://github.com/sunpy/ablog/pull/69

Removed the hard dependencies on `alabaster` and `sphinx-automodapi`.

Replaced `werkzeug` with `feedgen` due to the former removing ATOM support.

Version pin of `nbsphinx` has been removed.