http_client Clarify DNS resolver use for CURL

modules/http_client/README

@@ -183,6 +183,10 @@ Chapter 1. Admin Guide
    and get access to parts of the reply. This function has been ported
    from the utils module and now use the same libcurl functions.
 
+   The http_client module use the CURL library setting up connections. The
+   CURL library by default use the system configured DNS resolvers, not
+   the Kamailio resolver.
+
    The module is limited to using HTTP and HTTPS protocols.
 
 2. Dependencies

modules/http_client/doc/http_client_admin.xml

@@ -44,6 +44,11 @@
 	functions.
 	</para>
 	<para>
+	The http_client module use the CURL library setting up connections.
+	The CURL library by default use the system configured DNS resolvers,
+	not the Kamailio resolver.
+	</para>
+	<para>
 	The module is limited to using HTTP and HTTPS protocols.
 	</para>
 	</section>