bugzilla: more documentation fixes

Correct formatting of the possible values of bugzilla.version.
Fix typo and polish XMLRPC/email mode description.

hgext/bugzilla.py

@@ -40,18 +40,19 b' configuration must be readable by all Me'
 that the rights of that user are restricted in Bugzilla to the minimum
 necessary to add comments.
 
-Access via XMLRPC/email behaves uses XMLRPC to query Bugzilla, but sends
+Access via XMLRPC/email uses XMLRPC to query Bugzilla, but sends
 email to the Bugzilla email interface to submit comments to bugs.
 The From: address in the email is set to the email address of the Mercurial
 user, so the comment appears to come from the Mercurial user. In the event
 that the Mercurial user email is not recognised by Bugzilla as a Bugzilla
-user, the Bugzilla username and password used to log into Bugzilla are
-used instead as the source of the comment.
+user, the email associated with the Bugzilla username used to log into
+Bugzilla is used instead as the source of the comment.
 
 Configuration items common to all access modes:
 
 bugzilla.version
-  This access type to use. Values recognised are:
+  This access type to use. Values recognised are::
+
   xmlrpc       Bugzilla XMLRPC interface.
   xmlrpc+email Bugzilla XMLRPC and email interfaces.
   3.0          MySQL access, Bugzilla 3.0 and later.