[3.1.x] Fixed #32057 -- Doc'd HttpResponse.get()/items().

Backport of 0da212ffbf from master

docs/ref/request-response.txt

@@ -832,11 +832,20 @@ Methods
 
     Returns the value for the given header name. Case-insensitive.
 
+.. method:: HttpResponse.get(header, alternate=None)
+
+    Returns the value for the given header, or an ``alternate`` if the header
+    doesn't exist.
+
 .. method:: HttpResponse.has_header(header)
 
     Returns ``True`` or ``False`` based on a case-insensitive check for a
     header with the given name.
 
+.. method:: HttpResponse.items()
+
+    Acts like :meth:`dict.items` for HTTP headers on the response.
+
 .. method:: HttpResponse.setdefault(header, value)
 
     Sets a header unless it has already been set.