aap_python: note about use of pvs in docs

src/modules/app_python/doc/app_python_admin.xml

@@ -11,9 +11,9 @@
 <!-- Module User's Guide -->
 
 <chapter>
-    
+
     <title>&adminguide;</title>
-    
+
     <section>
 	<title>Overview</title>
 	<para>
@@ -122,7 +122,7 @@ modparam("app_python", "child_init_method", "my_child_init")
 	</section>
 
 	</section>
-	
+
     <section>
 	<title>Functions</title>
  	<section>
@@ -133,6 +133,9 @@ modparam("app_python", "child_init_method", "my_child_init")
 			Execute the Python function with the name given by the parameter 'method'.
 			Optionally can be provided a second string with parameters to be passed
 			to the Python function.
+	    </para>
+	    <para>
+			Both parameters can contain pseudo-variables.
 	    </para>
 		<example>
 		<title><function>python_exec</function> usage</title>
@@ -140,12 +143,13 @@ modparam("app_python", "child_init_method", "my_child_init")
 ...
 python_exec("my_python_function");
 python_exec("my_python_function", "my_params");
+python_exec("my_python_function", "$rU");
 ...
 </programlisting>
 	    </example>
 	</section>
-	
+
     </section>
-	
+
 </chapter>