Add note about mastodon to rules

next/rules.md

@@ -17,7 +17,8 @@ the past.
 
 Watch both [the IOCCC status page](../status.html) and the
 [@IOCCC mastodon feed](https://fosstodon.org/@ioccc) for information about
-future IOCCC openings.
+future IOCCC openings. Please be sure to check the feed every so often as unless
+you are mentioned you will **NOT** get a notification.
 
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