Fix formatting of GitHub issue template
There is actually an easier way to format comments, which doesn't
require a hack and also fixes the dispay in non-monospace fonts.
-[NOTICE]: <> ( )
-[NOTICE]: <> ( Please do *NOT* ask usage questions in Github issues. )
-[NOTICE]: <> ( )
-[NOTICE]: <> ( If your issue is not a feature request or bug report use: )
-[NOTICE]: <> ( https://groups.google.com/forum/#!forum/prometheus-users. If )
-[NOTICE]: <> ( you are unsure whether you hit a bug, search and ask in the )
-[NOTICE]: <> ( mailing list first. )
-[NOTICE]: <> ( )
-[NOTICE]: <> ( You can read more at: https://prometheus.io/community/ )
-[NOTICE]: <> ( )
+<!--
+
+ Please do *NOT* ask usage questions in Github issues.
+
+ If your issue is not a feature request or bug report use:
+ https://groups.google.com/forum/#!forum/prometheus-users. If
+ you are unsure whether you hit a bug, search and ask in the
+ mailing list first.
+
+ You can find more information at: https://prometheus.io/community/
+
+-->
**What did you do?**
