DOC: reorder CI control guidance [ci doc]

Author: rcomer

doc/devel/coding_guide.rst

@@ -360,20 +360,22 @@ will run on all supported platforms and versions of Python.
 
   .. _tox: https://tox.readthedocs.io/
 
-* If you know your changes do not need to be tested (this is very rare!), all
-  CIs can be skipped for a given commit by including ``[ci skip]`` or
-  ``[skip ci]`` in the commit message. If you know only a subset of CIs need
-  to be run (e.g., if you are changing some block of plain reStructuredText and
-  want only CircleCI to run to render the result), individual CIs can be
-  skipped on individual commits as well by using the following substrings
-  in commit messages:
-
-  - GitHub Actions: ``[skip actions]``
-  - AppVeyor: ``[skip appveyor]`` (must be in the first line of the commit)
-  - Azure Pipelines: ``[skip azp]``
-  - CircleCI: ``[skip circle]``
-
-  If you only want to run documentation CI you can pass ``[ci doc]``.
+* If you know only a subset of CIs need to be run, this can be controlled on
+  individual commits by including the following substrings in commit messages:
+
+  - If you only changed documentation, use ``[ci doc]`` to restrict the CI to
+    documentation checks.
+  - If you didn't change any documentation, use ``[skip circle]`` to skip the
+    documentation build check.
+  - Unit tests can be turned off for individual platforms with
+
+    - GitHub Actions: ``[skip actions]``
+    - AppVeyor: ``[skip appveyor]`` (must be in the first line of the commit)
+    - Azure Pipelines: ``[skip azp]``
+
+  - If you know your changes do not need to be tested at all (this is very
+    rare!), all CIs can be skipped by including ``[ci skip]`` or ``[skip ci]``.
+
 
 .. _pr-squashing: