Revert "Fixed a typo in the HTMLParser.feed docstrings" (#1771)

* Revert "Fixed a typo in the HTMLParser.feed docstrings. The docstring started with an 'r', like a The docstring was correct. I read the patch in opposite direction, as *adding* the "r" prefix.
This reverts commit 5ba18503.

Lib/html/parser.py

@@ -102,7 +102,7 @@ class HTMLParser(_markupbase.ParserBase):
         _markupbase.ParserBase.reset(self)
 
     def feed(self, data):
-        """Feed data to the parser.
+        r"""Feed data to the parser.
 
         Call this as often as you want, with as little or as much text
         as you want (may include '\n').