[bug] 5.0.0: sphinx warnings `reference target not found`

[kloczek]

On building my packages I'm using sphinx-build command with -n switch which shows warmings about missing references. These are not critical issues.
There are as well not only reference target not found warnings.
Here is the output with warnings:

+ /usr/bin/sphinx-build -n -T -b man docs build/sphinx/man
Running Sphinx v4.5.0
making output directory... done
building [mo]: targets for 0 po files that are out of date
building [man]: all manpages
updating environment: [new config] 7 added, 0 changed, 0 removed
reading sources... [100%] migrating
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/docs/clean.rst:332: ERROR: An option to autoclass is either unknown or has an invalid value: 'autodoc_preserve_defaults'
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/docs/goals.rst:156: ERROR: Unknown target name: "other vectors https://html5sec.org/#css".
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/docs/goals.rst:172: ERROR: Unknown target name: "browser leaks https://browserleaks.com/".
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/docs/goals.rst:173: ERROR: Unknown target name: "http leaks https://github.com/cure53/httpleaks".
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/docs/goals.rst:174: ERROR: Unknown target name: "xs leaks https://xsleaks.dev/".
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
writing... python-bleach.3 { clean linkify goals dev changes migrating } /home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/__init__.py:docstring of bleach.clean:: WARNING: py:class reference target not found: CSSSanitizer
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/docs/clean.rst:291: WARNING: py:class reference target not found: bleach.css_sanitizer.CSSSanitizer
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/docs/clean.rst:323: WARNING: py:class reference target not found: bleach.css_sanitizer.CSSSanitizer
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/sanitizer.py:docstring of bleach.sanitizer.Cleaner:: WARNING: py:class reference target not found: CSSSanitizer
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/docs/clean.rst:353: WARNING: py:class reference target not found: bleach.sanitizer.BleachSanitizingFilter
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/sanitizer.py:docstring of bleach.sanitizer.BleachSanitizerFilter:: WARNING: py:class reference target not found: Treewalker
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/sanitizer.py:docstring of bleach.sanitizer.BleachSanitizerFilter:: WARNING: py:class reference target not found: CSSSanitizer
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/linkifier.py:docstring of bleach.linkifier.Linker:: WARNING: py:class reference target not found: re
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/linkifier.py:docstring of bleach.linkifier.Linker:: WARNING: py:class reference target not found: re
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/linkifier.py:docstring of bleach.linkifier.Linker:: WARNING: py:class reference target not found: list-of-strings
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/linkifier.py:docstring of bleach.linkifier.LinkifyFilter:: WARNING: py:class reference target not found: TreeWalker
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/linkifier.py:docstring of bleach.linkifier.LinkifyFilter:: WARNING: py:class reference target not found: re
/home/tkloczko/rpmbuild/BUILD/bleach-5.0.0/bleach/linkifier.py:docstring of bleach.linkifier.LinkifyFilter:: WARNING: py:class reference target not found: re
done
build succeeded, 18 warnings.

[willkg]

Thank you for this!

If someone else wants to throw together a PR, I'd be much obliged. Otherwise, I can probably take a look at it this month.