Updated documentation and comments for RFC updates.

- Updated references to RFC 1123 to RFC 5322
  - Only partial as RFC 5322 sort of sub-references RFC 1123.
- Updated references to RFC 2388 to RFC 7578
  - Except RFC 2388 Section 5.3 which has no equivalent.
- Updated references to RFC 2396 to RFC 3986
- Updated references to RFC 2616 to RFC 9110
- Updated references to RFC 3066 to RFC 5646
- Updated references to RFC 7230 to RFC 9112
- Updated references to RFC 7231 to RFC 9110
- Updated references to RFC 7232 to RFC 9110
- Updated references to RFC 7234 to RFC 9111
- Tidied up style of text when referring to RFC documents

docs/ref/models/instances.txt

@@ -848,7 +848,7 @@ track down every place that the URL might be created. Specify it once, in
 
 .. note::
     The string you return from ``get_absolute_url()`` **must** contain only
-    ASCII characters (required by the URI specification, :rfc:`2396#section-2`)
+    ASCII characters (required by the URI specification, :rfc:`3986#section-2`)
     and be URL-encoded, if necessary.
 
     Code and templates calling ``get_absolute_url()`` should be able to use the

docs/ref/models/querysets.txt

@@ -2174,7 +2174,7 @@ Finally, a word on using ``get_or_create()`` in Django views. Please make sure
 to use it only in ``POST`` requests unless you have a good reason not to.
 ``GET`` requests shouldn't have any effect on data. Instead, use ``POST``
 whenever a request to a page has a side effect on your data. For more, see
-:rfc:`Safe methods <7231#section-4.2.1>` in the HTTP spec.
+:rfc:`Safe methods <9110#section-9.2.1>` in the HTTP spec.
 
 .. warning::