Add release notes for Djblets 1.0.1.

Review Request #9422 — Created Dec. 4, 2017 and submitted — Latest diff uploaded

Information

Djblets
release-1.0.x
e64ef43...

Reviewers

This is a small release focusing only on the fix for the disappearance
of avatar backends. Other fixes that are in progress will be pushed to
future patch releases.

Build the docs and read through them. Checked for spelling and build
errors.