* [stable-2.14] Convert non-docs *.rst files to *.md (#81217)
* Rename README.rst to README.md
* Change README format from reStructuredText to Markdown
* Fix whitespace in README.md
* Update setup.cfg to use README.md
* Replace changelog placeholder with README.md
* Update package-data sanity test
(cherry picked from commit 38e50c9f81)
Co-authored-by: Matt Clay <matt@mystile.com>
* Remove README.rst from MANIFEST.in