🎨 Overhaul changelog to plain reStructuredText (#484)

Remove releases in favor of a more sphinx-issues and basic reST structuring.
https://github.com/bitprophet/releases was inflexible in cases where we used
v<versionnumber> (v1.2.2) and wanted to link back to master.

Issue / PR:
- bitprophet/releases#54
- bitprophet/releases#76

Other issues is how the behavior did more than styling and issue linking,
sometimes patches only intended for minor releases were also added
to minor releases. Regardless of what it intended to do, it wasn't
compatible with how releases were cut. It does more than the projects
I added to needed.

Instead of using reST sections, it used list items to represent versions. 
Which then go on to build html that a section would anyway.  This feels
out of place when separating versions.

Custom roles used in releases were way too much investment for a
changelog. It'd be worth seeing if the same job could be done by
iterating over node test and linking to issues like GitHub does. e.g #484

Author: tony