Add docs for types

Add a page to pull in the docstrings for the option types,
and make the docstring changes in the module necessary for
that to work properly.

Also fix a formatting issue in the docs for the cfg module.

Change-Id: Ib1cf24e59ecc3592d3b703f99659f4a0fdbc7f5c
Fix misspellings in oslo.config

Fix misspellings detected by:
* pip install misspellings
* git ls-files | grep -v locale | misspellings -f -

Change-Id: I96a3e5717cbce66c19ead15a9e491fe4a44f6e88
Closes-Bug: #1257295
Merge "Add docs for types"
Merge "Fix misspellings in oslo.config"