Prior to this the depth of the bookmarks is too low, one does not even
get to see for example what are the built-in extensions offered by
Sphinx.
Similarly the LaTeX created table of contents has not enough depth.
Dozens of contiguous pages from our documentation get only a single
link, it is very hard for newcomer to get some feeling of the scope of
Sphinx. With a more detailed table of contents (be it inside the PDF or
via the collapsable bookmark panel of PDF viewer) learning Sphinx is
easier.
Reorder this to flow a little better and re-add the CONTRIBUTING
document, which now simply points to the main documentation.
Signed-off-by: Stephen Finucane <stephen@that.guru>
