Add release notes for Review Board 2.0.20.

Review Request #7624 — Created Sept. 13, 2015 and submitted

Information

Review Board
release-2.0.x

Reviewers

These cover all the e-mail, diff viewer, file attachment, etc. fixes
that have gone into this release.

It also contains a variation on the prior security announcement,
instructing people on how to install Django 1.6.11.1.

Built the docs and read through them.

reviewbot
  1. Tool: PEP8 Style Checker
    Ignored Files:
        docs/releasenotes/2.0.20.rst
        docs/releasenotes/index.rst
        AUTHORS
    
    
    
    Tool: Pyflakes
    Ignored Files:
        docs/releasenotes/2.0.20.rst
        docs/releasenotes/index.rst
        AUTHORS
    
    
  2. 
      
david
  1. Ship It!
  2. 
      
chipx86
reviewbot
  1. Tool: Pyflakes
    Ignored Files:
        docs/releasenotes/2.0.20.rst
        docs/releasenotes/index.rst
        AUTHORS
    
    
    
    Tool: PEP8 Style Checker
    Ignored Files:
        docs/releasenotes/2.0.20.rst
        docs/releasenotes/index.rst
        AUTHORS
    
    
  2. 
      
chipx86
Review request changed
Status:
Completed
Change Summary:
Pushed to release-2.0.x (ba2fc89)