Add release notes for RBTools 0.7.11.

Review Request #9429 — Created Dec. 6, 2017 and submitted — Latest diff uploaded

Information

RBTools
release-0.7.x
89b281f...

Reviewers

This is primarily a bug fix release, covering some fixes for tfs-git,
rbt post, and rbt install. It also introduces some better debug
information when posting changes and makes use of Git-style diffs when
posting changes for Mercurial.

Built the docs and checked for build and spelling errors.