Add gender-neutrality to documentation standards

Modeled after changes made to the Django project: django/django@c0a2daa

Author: epochblue

contributing/documentation/standards.rst

@@ -125,6 +125,14 @@ Language Standards
 * Do not use `Serial (Oxford) Commas`_;
 * You should use a form of *you* instead of *we* (i.e. avoid the first person
  point of view: use the second instead).
+* When referencing a hypothetical person, such as "a user with a session cookie", gender-neutral
+ pronouns (they/their/them) should be used. For example, instead of:
+
+ * he or she, use they
+ * him or her, use them
+ * his or her, use their
+ * his or hers, use theirs
+ * himself or herself, use themselves
 
 .. _`the Sphinx documentation`: http://sphinx-doc.org/rest.html#source-code
 .. _`Twig Coding Standards`: http://twig.sensiolabs.org/doc/coding_standards.html