Documentation includes reference manual twice
It looks like Id112b2b8f20eb5de3b704bc2b27ab7ce55f035ff did not work as it should and leads to the reference manual being included twice in the table of contents.
Change Table of contents depth
Changes the table of contents depth on the main
GROMACS documentation to only show the headers by default, to reduce
clutter on the main page.
This also addresses the issue in #2716, but I'll keep this up for
discussion as it is a major change to what kind of information is
available at the main documentation page.