2.1.0: 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.
Here is the output with warnings:

Details

+ /usr/bin/sphinx-build -n -T -b man docs build/sphinx/man
Running Sphinx v7.1.2
WARNING: Invalid configuration value found: 'language = None'. Update your configuration to a valid language code. Falling back to 'en' (English).
making output directory... done
building [mo]: targets for 0 po files that are out of date
writing output...
building [man]: all manpages
updating environment: [new config] 9 added, 0 changed, 0 removed
reading sources... [100%] valuesorteddict
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
writing... python-sortedcollections.3 { valuesorteddict itemsorteddict nearestdict ordereddict orderedset indexabledict indexableset segmentlist } /home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/recipes.py:docstring of sortedcollections.recipes.ValueSortedDict.__reduce__:3: WARNING: py:func reference target not found: SortedDict.__init__
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/nearestdict.py:docstring of sortedcollections.nearestdict.NearestDict:3: WARNING: py:class reference target not found: SortedDict
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/nearestdict.py:docstring of sortedcollections.nearestdict.NearestDict:8: WARNING: py:attr reference target not found: NearestDict.NEAREST
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/nearestdict.py:docstring of sortedcollections.nearestdict.NearestDict.__init__:3: WARNING: py:attr reference target not found: NearestDict.NEAREST_NEXT
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/nearestdict.py:docstring of sortedcollections.nearestdict.NearestDict.__init__:3: WARNING: py:attr reference target not found: NearestDict.NEAREST
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/nearestdict.py:docstring of sortedcollections.nearestdict.NearestDict.__init__:3: WARNING: py:attr reference target not found: NearestDict.NEAREST_PREV
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/nearestdict.py:docstring of sortedcollections.nearestdict.NearestDict.__init__:3: WARNING: py:attr reference target not found: NearestDict.NEAREST
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/nearestdict.py:docstring of sortedcollections.nearestdict.NearestDict.__init__:10: WARNING: py:class reference target not found: SortedDict
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/nearestdict.py:docstring of sortedcollections.nearestdict.NearestDict.__init__:11: WARNING: py:class reference target not found: SortedDict
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/ordereddict.py:docstring of collections.abc.MutableMapping.update:1: WARNING: py:class reference target not found: None.  Update D from mapping/iterable E and F.
/home/tkloczko/rpmbuild/BUILD/python-sortedcollections-2.1.0/sortedcollections/recipes.py:docstring of sortedcollections.recipes.IndexableSet.__reduce__:3: WARNING: py:func reference target not found: SortedSet.__init__
done
build succeeded, 12 warnings.

You can peak on fixes that kind of issues in other projects
RDFLib/rdflib-sqlalchemy#95
RDFLib/rdflib#2036
click-contrib/sphinx-click@abc31069
frostming/unearth#14
jaraco/cssutils#21
latchset/jwcrypto#289
latchset/jwcrypto#289
pypa/distlib@98b9b89f
pywbem/pywbem#2895
sissaschool/elementpath@bf869d9e
sissaschool/xmlschema@42ea98f2
sqlalchemy/sqlalchemy@5e88e6e8