Resolves sphinx-doc#13119: Add solution to referencing glossary terms…

… with alternate word forms.

doc/usage/restructuredtext/directives.rst

@@ -1156,6 +1156,47 @@ Glossary
    text only have "term" part. In this case, translated "localized term" will be
    categorized in "key" group.
 
+   **Referencing Glossary Terms with Other Terms:**
+
+   If you need to link to a glossary term using an alternate form of the word (e.g.
+   the gloosary term is *"source directory"* and you want to link to it in a
+   paragraph using the word *"root directory"*), you can do so by adding an "explicit
+   link target" to the glossary term using the same syntax as is used to add an
+   "explicit link target" to items in a list::
+
+      .. glossary::
+
+         environment
+            A structure where information about all documents under the root is
+            saved, and used for cross-referencing.  The environment is pickled
+            after the parsing stage, so that successive runs only need to read
+            and parse new and changed documents.
+
+            .. _source directory:
+            .. _root directory:
+
+         source directory
+            The directory which, including its subdirectories, contains all
+            source files for one Sphinx project.
+
+   .. note::
+
+      The explicit link target must be indented even with the definition above it.
+
+   That term can now be linked to like this::
+
+      All source files for this project is required to be under the
+      :ref:`root directory <source directory>` of the project.
+
+   or::
+
+      All source files for this project is required to be under the
+      :ref:`root directory` of the project.
+
+   .. note::
+
+      This does not work at this time for the first glossary entry since the glossary
+      parser tries to interpret the "explicit link target" as a glossary entry.
 
    .. versionchanged:: 1.1
       Now supports multiple terms and inline markup in terms.