Author: Uwe L. Korn <uwelk@xhochy.com>
Author: Korn, Uwe <Uwe.Korn@blue-yonder.com>
Author: Wes McKinney <wesm+git@apache.org>

Closes #2856 from xhochy/doc-merge and squashes the following commits:

5b687ffa7 <Wes McKinney> Add simple README for the format/ directory
071d16ad7 <Uwe L. Korn> Move format specifications back to /format/
337088bfd <Uwe L. Korn> Review comments
fbe99c96c <Uwe L. Korn> Add more C++ docs
78a5eaf4b <Uwe L. Korn> Fix Python docs build
0b4dd3341 <Uwe L. Korn> Rename doc to docs
918e76244 <Uwe L. Korn> Convert format docs to reST
7aeff65ef <Uwe L. Korn> Add doc generation to docker-compose
185cba8fb <Uwe L. Korn> Add pre-commit check for RAT
671d24466 <Uwe L. Korn> Fix references to format documents
bdd824c87 <Uwe L. Korn> Move doc to top-level
985d42806 <Uwe L. Korn> Move Sphinx doc to top-level directory
f7d5e92d9 <Uwe L. Korn> Build C++ API docs
7850db8a6 <Uwe L. Korn> Add breathe as a requirement
d4cf54259 <Uwe L. Korn> Fix linter issues
fd75660e6 <Korn, Uwe> Fix Sphinx build for sphinx>=1.8
9be6fbe6f <Korn, Uwe> Merge C++ and Python documentation