Most of these maintainers already have the necessary approval
and merge privileges. I'll add the rest once this PR goes through.
I've also removed some text in a few files that were blatantly outdated.
Also removed the now outdated pullapprove.
Signed-off-by: Sugu Sougoumarane <ssougou@gmail.com>
The prevailing convention on GitHub seems to be .md
Also by moving CONTRIBUTING.md to the root, GitHub will automatically
link to it when someone tries to contribute:
https://github.com/blog/1184-contributing-guidelines