github: also add a link to the list of latest releases

wm4 · wm4 · commit e2b955121318 · 2017-05-05T12:37:34.000+02:00
Since some users apparently can't figure this out.
diff --git a/.github/ISSUE_TEMPLATE b/.github/ISSUE_TEMPLATE
@@ -1,6 +1,7 @@
 ### mpv version and platform
 
 If you're not using git master or the latest release, update.
+Releases are listed here: https://github.com/mpv-player/mpv/releases
 
 ### Reproduction steps
 
