gh-117225: Document colour use in doctest (#118268)

Author: hugovk

Doc/using/cmdline.rst

@@ -632,11 +632,11 @@ behavior can be controlled by setting different environment variables.
 
 Setting the environment variable ``TERM`` to ``dumb`` will disable color.
 
-If the environment variable ``FORCE_COLOR`` is set, then color will be
+If the |FORCE_COLOR|_ environment variable is set, then color will be
 enabled regardless of the value of TERM. This is useful on CI systems which
 aren’t terminals but can still display ANSI escape sequences.
 
-If the environment variable ``NO_COLOR`` is set, Python will disable all color
+If the |NO_COLOR|_ environment variable is set, Python will disable all color
 in the output. This takes precedence over ``FORCE_COLOR``.
 
 All these environment variables are used also by other tools to control color
@@ -645,6 +645,14 @@ output. To control the color output only in the Python interpreter, the
 precedence over ``NO_COLOR``, which in turn takes precedence over
 ``FORCE_COLOR``.
 
+.. Apparently this how you hack together a formatted link:
+
+.. |FORCE_COLOR| replace:: ``FORCE_COLOR``
+.. _FORCE_COLOR: https://force-color.org/
+
+.. |NO_COLOR| replace:: ``NO_COLOR``
+.. _NO_COLOR: https://no-color.org/
+
 Options you shouldn't use
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 

Doc/whatsnew/3.13.rst

@@ -100,10 +100,18 @@ Improved Error Messages
 
 * The interpreter now colorizes error messages when displaying tracebacks by default.
   This feature can be controlled via the new :envvar:`PYTHON_COLORS` environment
-  variable as well as the canonical ``NO_COLOR`` and ``FORCE_COLOR`` environment
+  variable as well as the canonical |NO_COLOR|_ and |FORCE_COLOR|_ environment
   variables. See also :ref:`using-on-controlling-color`.
   (Contributed by Pablo Galindo Salgado in :gh:`112730`.)
 
+.. Apparently this how you hack together a formatted link:
+
+.. |FORCE_COLOR| replace:: ``FORCE_COLOR``
+.. _FORCE_COLOR: https://force-color.org/
+
+.. |NO_COLOR| replace:: ``NO_COLOR``
+.. _NO_COLOR: https://no-color.org/
+
 * A common mistake is to write a script with the same name as a
   standard library module. When this results in errors, we now
   display a more helpful error message:
@@ -439,6 +447,12 @@ doctest
   :attr:`doctest.TestResults.skipped` attributes.
   (Contributed by Victor Stinner in :gh:`108794`.)
 
+* Color is added to the output by default.
+  This can be controlled via the new :envvar:`PYTHON_COLORS` environment
+  variable as well as the canonical |NO_COLOR|_ and |FORCE_COLOR|_ environment
+  variables. See also :ref:`using-on-controlling-color`.
+  (Contributed by Hugo van Kemenade in :gh:`117225`.)
+
 email
 -----