app_lua: docs - more details about lua_run() params

(cherry picked from commit f1f6c30)

src/modules/app_lua/doc/app_lua_admin.xml

@@ -333,24 +333,27 @@ if(!lua_dostring("sr.log([[err]], [[----------- Hello World from $fU\n]])"))
 
 	<section id="app_lua.f.lua_run">
 	    <title>
-		<function moreinfo="none">lua_run(function, params)</function>
+		<function moreinfo="none">lua_run(func [, params])</function>
 	    </title>
 	    <para>
-		Execute the Lua function 'func' giving params as parameters. There
-		can be up to 3 string parameters. The function must exist in the
+		Execute the Lua function 'func' giving 'params' as parameters. There
+		can be up to 3 string parameters after 'func' (overall, max 4 params,
+		first is the function). The function must exist in the Lua
 		script loaded at startup via parameter 'load'. Parameters can be
 		strings with pseudo-variables that are evaluated at runtime.
 	    </para>
 		<example>
 		<title><function>lua_run</function> usage</title>
 		<programlisting format="linespecific">
 ...
-if(!lua_run("sr_append_fu_to_reply"))
-{
+if(!lua_run("sr_append_fu_to_reply")) {
     xdbg("SCRIPT: failed to execute lua function!\n");
 }
 ...
-lua_run("lua_funcx", "$rU", "2");
+lua_run("lua_funcx0");
+lua_run("lua_funcx1", "$rU");
+lua_run("lua_funcx2", "$rU", "2");
+lua_run("lua_funcx3", "$rU", "2", "$si");
 ...
 </programlisting>
 	    </example>