Changelog updates
Created by: christinaforney
- Added some missing links (there are still some missing for entries - I focused on the added section).
- Updated to match language from https://github.com/sourcegraph/about/pull/583
- @lguychard and @efritz - the Perl and Scala syntax highlighting notes are in Added and Fixed sections - should they be in the same section? Or were the changes different so they should be categorized differently?