Updated documentation for the optional CID parameter with CALLERID

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Merged revisions 341664 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 341665 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@341666 65c4cc65-6c06-0410-ace0-fbb531ad65f3

funcs/func_callerid.c

@@ -120,7 +120,8 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 				</enumlist>
 			</parameter>
 			<parameter name="CID">
-				<para>Optional Caller*ID</para>
+				<para>Optional Caller*ID to parse instead of using the Caller*ID from the
+				channel. This paramater is only optional when reading the Caller*ID.</para>
 			</parameter>
 		</syntax>
 		<description>