Updates for RTOFSv2.4.3 operational upgrade (#2800)

Updates for upstream RTOFS upgrade to v2.4.3. 

A new GFS version results from this upgrade due to second digit RTOFS version
update and resulting COM path update (`../rtofs/v2.4`). No other change in this
operational upgrade.

Also some requested cleanup/decluttering of release notes.
Have deleted all older release notes and renamed most recent version
notes to `Release_Notes.md`. Future implementations will update this
same file instead of making a new file.

Refs #2320