CHANGELOG Minor copyedit (typo)
tests - Move tests for disabled features to separate file
tests - Add some manual test cases; copyedit
README - Copyedit

Arrange sections, add links, add section headers,
copyedit, and add intro description.
Let's mention the installation link here too.
Pers_pref - Do *not* toggle the "contact in private browsing mode" box when "Always ask" box is changed

Discussed as part of GH #135. These boxes should not be linkd.