Fix the Sphinx html_last_updated_fmt for Python3.
The html_last_updated_fmt option is interpeted as a
byte string in python3, causing Sphinx build to break.
This patch makes it utf-8 string.
Change-Id: I6cde9bb1f815bae91378772626142dd7645188d7
This patch will create the initial directory and index for the api reference
documentation (using the new guidelines) for the Octavia API.
Change-Id: Id5fbe569acfe7348f4f9dfc9cbef49834ea824c3
Partial-Bug: #1558385