Fixed #22141 -- Added a spelling checker for documentation.

docs/internals/contributing/writing-documentation.txt

@@ -348,3 +348,27 @@ look better:
   (that's a tilde) to get just the "last bit" of that path. So
   ``:class:`~django.contrib.contenttypes.models.ContentType``` will just
   display a link with the title "ContentType".
+
+Spelling check
+--------------
+
+Before you commit your docs, it's a good idea to run the spelling checker.
+You'll need to install a couple packages first:
+
+* `pyenchant <https://pypi.python.org/pypi/pyenchant/>`_ (which requires
+  `enchant <http://www.abisource.com/projects/enchant/>`_)
+
+* `sphinxcontrib-spelling
+  <https://pypi.python.org/pypi/sphinxcontrib-spelling/>`_
+
+Then from the ``docs`` directory, run ``make spelling``. Wrong words (if any)
+along with the file and line number where they occur will be saved to
+``_build/spelling/output.txt``.
+
+If you encounter false-positives (error output that actually is correct), do
+one of the following:
+
+* Surround inline code or brand/technology names with grave accents (`).
+* Find synonyms that the spell checker recognizes.
+* If, and only if, you are sure the word you are using is correct - add it
+  to ``docs/spelling_wordlist`` (please keep the list in alphabetical order).