- Remove all genindex.rst files, these are generated and should not
exist in our source.
- Fix the HTML templates so the local specialisation works.
- Add a index link to the sidebar for HTML.
Note, there is no TOC entry for the index in the PDF output and I
cannot figure out how to add one.
Closes#3503
The content was manually converted from Asciidoc to Sphinx and
there are some areas which remain to be done. Specifically
there are some tables and embedded links which are known
to remain but there are almost certainly other things to
clean up.
