DOC Document 'all random seeds' commit marker (scikit-learn#32553)

Co-authored-by: Olivier Grisel <[email protected]>
Co-authored-by: Loïc Estève <[email protected]>

Author: 3 people

doc/developers/contributing.rst

@@ -584,6 +584,9 @@ Commit Message Marker  Action Taken by CI
 [pyodide]              Build & test with Pyodide
 [azure parallel]       Run Azure CI jobs in parallel
 [float32]              Run float32 tests by setting `SKLEARN_RUN_FLOAT32_TESTS=1`. See :ref:`environment_variable` for more details
+[all random seeds]     Run tests using the `global_random_seed` fixture with all random seeds.
+                       See `this <https://github.com/scikit-learn/scikit-learn/issues/28959>`_
+                       for more details about the commit message format
 [doc skip]             Docs are not built
 [doc quick]            Docs built, but excludes example gallery plots
 [doc build]            Docs built including example gallery plots (very long)