Update documentation

Author: andreydp

quickfixj-core/src/main/doc/usermanual/usage/configuration.html

@@ -467,7 +467,7 @@ <H3>QuickFIX Settings</H3>
   <TR ALIGN="left" VALIGN="middle">
       <TD><I>FirstFieldInGroupIsDelimiter</I></TD>
       <TD>Session validation setting for enabling whether first found field in repeating group will be used as
-          delimiter. Values are "Y" or "N". Default is "N".</TD>
+          delimiter. Values are "Y" or "N". Default is "N". ValidateUnorderedGroupFields should be set to "N"</TD>
       <TD>Y<br>
           N</TD>
       <TD>N</TD>