Update docs

Co-authored-by: Kevin Klein <7267523+kklein@users.noreply.github.com>

Author: SimonLangerQC

src/datajudge/requirements.py

@@ -282,7 +282,7 @@ def add_uniques_equality_constraint(
         It can be configured in more detail by supplying a custom ``filter_func`` function.
         Some exemplary implementations are available in this module as :func:`~datajudge.utils.filternull_element`,
         :func:`~datajudge.utils.filternull_never`, :func:`~datajudge.utils.filternull_element_or_tuple_all`, :func:`~datajudge.utils.filternull_element_or_tuple_any`.
-        Passing None as the argument is equivalent to ``datajudge.utils.filternull_element``, but triggers a warning.
+        Passing ``None`` as the argument is equivalent to :func:`~datajudge.utils.filternull_element` but triggers a warning.
         The deprecated default may change in future versions.
         To silence the warning, set ``filter_func`` explicitly.