Added a Discord link to BUGS.txt

Author: slouken

BUGS.txt

@@ -11,6 +11,9 @@ You may also find help at the SDL forums/mailing list:
 
     https://discourse.libsdl.org/
 
-Bug reports are welcome here, but we really appreciate if you use the issue
- tracker, as bugs discussed on the mailing list may be forgotten or missed.
+or on Discord:
+
+    https://discord.com/invite/BwpFGBWsv8
+
+Bug reports are welcome here, but we really appreciate if you use the issue tracker, as bugs discussed on the mailing list or Discord may be forgotten or missed.