gh-35056: Minor documentation formating and punctuation fixes.

Author: aisipos

Doc/whatsnew/3.15.rst

@@ -837,7 +837,7 @@ http.server
   HTTP responses.
   (Contributed by Anton I. Sipos in :gh:`135057`.)
 
-* Add a ``-H`` or ``--header`` flag to the :program:`python -m http.server`
+* Add a ``-H/--header`` option to the :program:`python -m http.server`
   command-line interface to support custom headers in HTTP responses.
   (Contributed by Anton I. Sipos in :gh:`135057`.)
 

Lib/http/server.py

@@ -758,7 +758,7 @@ def do_HEAD(self):
             f.close()
 
     def _send_extra_response_headers(self):
-        """Send the headers stored in self.extra_response_headers"""
+        """Send the headers stored in self.extra_response_headers."""
         if self.extra_response_headers is not None:
             for header, value in self.extra_response_headers:
                 self.send_header(header, value)