add tcp_accept_no_cl=yes to xhttp description

modules/xhttp/doc/xhttp_admin.xml

@@ -79,6 +79,21 @@
 			</itemizedlist>
 		</para>
 	</section>
+	<section>
+		<title>&kamailio; Core Settings</title>
+		<para>
+		SIP requires a Content-Length header for TCP transport. But most HTTP clients do not
+		set the content length for normal GET requests. Therefore, the core must be configured
+		to allow incoming requests without content length header:
+			<itemizedlist>
+			<listitem>
+			<para>
+				<emphasis>tcp_accept_no_cl=yes</emphasis>
+			</para>
+			</listitem>
+			</itemizedlist>
+		</para>
+	</section>
 	<section>
 		<title>External Libraries or Applications</title>
 		<para>