Merge r957613 from trunk:

better error message for db names, closes COUCHDB-741 thanks Frank

git-svn-id: https://svn.apache.org/repos/asf/couchdb/branches/0.11.x@957971 13f79535-47bb-0310-9956-ffa450edef68

src/couchdb/couch_httpd.erl

@@ -726,7 +726,7 @@ error_info({bad_ctype, Reason}) ->
 error_info({error, illegal_database_name}) ->
     {400, <<"illegal_database_name">>, <<"Only lowercase characters (a-z), "
         "digits (0-9), and any of the characters _, $, (, ), +, -, and / "
-        "are allowed">>};
+        "are allowed. Must begin with a letter.">>};
 error_info({missing_stub, Reason}) ->
     {412, <<"missing_stub">>, Reason};
 error_info({Error, Reason}) ->