configitems: register the 'email.reply-to' config

mercurial/configitems.py

@@ -206,6 +206,9 b" coreconfigitem('email', 'from',"
 coreconfigitem('email', 'method',
     default='smtp',
 )
+coreconfigitem('email', 'reply-to',
+    default=None,
+)
 coreconfigitem('experimental', 'allowdivergence',
     default=False,
 )