Update License and Help sections

There's an official License file now, so no need to specify this in the
README. And now this project has other maintainers, it's better for the
few support queries to go somewhere public.

README.md

@@ -73,12 +73,7 @@ to wherever you put this script:
 tarsnap --dry-run --quiet --print-stats --humanize-numbers -C / -c $backuptargets 2>&1
 ```
 
-License
--------
-
-This is free and unencumbered software released into the public domain.
-
 Help
 ----
 
-Open a Github issue, or you can email me (<alex@jurkiewi.cz>).
+Open a [Github issue](https://github.com/alexjurkiewicz/acts/issues).