Sphinx was displaying "WARNING: document isn't included in any toctree"
for files we just don't want in the TOC. We can hide them from the index,
but the rtd theme defaults to display hidden index entries in the nav bar.
This commit excludes these files from such warnings, and patches layout.html
so that hidden index entries stay hidden from the navigation sidebar.
This commit also moves password-strength.md under docs/production and
adds it as a hidden entry in production/index.rst.
Fixes#7417.
This commit helps reduce clutter on the navigation sidebar.
Creates new directories and moves relevant files into them.
Modifies index.rst, symlinks, and image paths accordingly.
This commit also enables expandable/collapsible navigation items,
renames files in docs/development and docs/production,
modifies /tools/test-documentation so that it overrides a theme setting,
Also updates links to other docs, file paths in the codebase that point
to developer documents, and files that should be excluded from lint tests.
Note that this commit does not update direct links to
zulip.readthedocs.io in the codebase; those will be resolved in an
upcoming follow-up commit (it'll be easier to verify all the links
once this is merged and ReadTheDocs is updated).
Fixes#5265.