development list has moved to forum

INSTALL.txt

@@ -29,12 +29,13 @@ To compile and install SDL:
     2.  Look at the example programs in ./test, and check out the online
         documentation at https://wiki.libsdl.org/
 
-    3.  Join the SDL developer mailing list by sending E-mail to
-    	sdl-request@libsdl.org
-        and put "subscribe" in the subject of the message.
+    3.  Join the SDL developer discussions, sign up on 
+        https://discourse.libsdl.org/
+        and go to the development forum
+        https://discourse.libsdl.org/c/sdl-development/6
 
-        Or alternatively you can use the web interface:
-            https://www.libsdl.org/mailing-list.php
+    4.  Sign up for the announcement list through the web interface:
+        https://www.libsdl.org/mailing-list.php
 
 That's it!
 Sam Lantinga <slouken@libsdl.org>