#21815: Make the doc change match what I actually did.

Doc/library/imaplib.rst

@@ -509,8 +509,8 @@ An :class:`IMAP4` instance has the following methods:
       create such tags.  Although it is an RFC violation and IMAP clients and
       servers are supposed to be strict, imaplib nontheless continues to allow
       such tags to be created for backward compatibility reasons, and as of
-      python 3.5.2/3.6.0, handles them if they are sent from the server, since
-      this improves real-world compatibility.
+      python 3.6, handles them if they are sent from the server, since this
+      improves real-world compatibility.
 
 .. method:: IMAP4.subscribe(mailbox)