topoh: docs for mask_mode parameter

src/modules/topoh/doc/topoh_admin.xml

@@ -133,6 +133,29 @@ modparam("topoh", "mask_ip", "192.168.0.1")
 ...
 modparam("topoh", "mask_callid", 1)
 ...
+</programlisting>
+		</example>
+	</section>
+	<section id="topoh.p.mask_mode">
+		<title><varname>mask_mode</varname> (integer)</title>
+		<para>
+			Control when and what parts of SIP message are masked.
+		</para>
+		<para>
+			It works as a bitmask value. The following options are available:
+			(1) - skip masking Contact headers in 3XX (redirect) replies.
+		</para>
+		<para>
+		<emphasis>
+			Default value is 0.
+		</emphasis>
+		</para>
+		<example>
+		<title>Set <varname>mask_mode</varname> parameter</title>
+		<programlisting format="linespecific">
+...
+modparam("topoh", "mask_mode", 1)
+...
 </programlisting>
 		</example>
 	</section>