Changelog markup fixes, refs #682 

Release 3.39 Refs #688

Fix underline length, refs #656 

Release 3.38 Refs #628, #633, #643, #644

Release 3.38a0 Refs #643

Release 3.37 Refs #618, #619, #620, #621, #630, #632

Release 3.36 Refs #344, #604, #606

More 3.35.2 release notes Refs #433, #522, #596, #598

Release notes for 3.35.1, refs #592 

Fixed two typos in the release notes