Add some basic docs around releasing the theme.
Add some basic docs around releasing the theme.

This just covers the basic tasks that I know need to happen,
feel free to suggest other improvements.

mitya57/sphinx_rtd_theme,mitya57/sphinx_rtd_theme,mitya57/sphinx_rtd_theme,snide/sphinx_rtd_theme,snide/sphinx_rtd_theme,snide/sphinx_rtd_theme,snide/sphinx_rtd_theme,mitya57/sphinx_rtd_theme