[Checkers] Suggestions for changelogs

[Michael Ernst]

I have a suggestion about writing change logs when making a new release.
Please write the changes in the order that is likely to be of most interest
to users.  In particular, write user-visible changes first, and then write
bug fixes or internal changes.  I've made a few small edits to
annotations/checkers/changelog-checkers.txt to organize it better (and to
fix a typo and to remove words that contribute nothing).

                    -Mike