Update RELEASENOTES.md and CHANGES.md for 2.0.1RC

Ran ./release-doc-maker/releasedocmaker.py -p HBASE --fileversions -v 2.0.1 -l --sortorder=newer --skip-credits in yetus checkout and added results to CHANGES/RELEASENOTES via careful insert (remember that markup doesn't like apache license as first thing in file so respect that insertion – see instructions in comment at head of these files for how to add version changes).