README: add a link to wiki, how to set up audio redirection

README.md

@@ -29,7 +29,7 @@ RDP transport is encrypted using TLS by default.
 
 ### Access to Remote Resources
  * two-way clipboard transfer (text, bitmap, file)
- * audio redirection
+ * audio redirection ([requires to build additional modules](https://github.com/neutrinolabs/xrdp/wiki/How-to-set-up-audio-redirection))
  * drive redirection (mount local client drives on remote machine)
 
 ## Quick Start
@@ -114,6 +114,11 @@ make
 sudo make install
 ```
 
+If you want to use audio redirection, you need to build and install additional
+pulseaudio modules. The build instructions can be found at wiki.
+
+* [How to set up audio redirection](https://github.com/neutrinolabs/xrdp/wiki/How-to-set-up-audio-redirection)
+
 ## Directory Structure
 
 ```