Add release notes for RBTools 0.7.8.
Review Request #8588 — Created Jan. 3, 2017 and submitted — Latest diff uploaded
This covers the work done on the installers for Windows and macOS, as well as the Unicode fixes and improvements to rbt setup-repo. It's a smaller release, but an important one from an installer standpoint.
Built the docs and read through them.
Checked for spelling errors.