Merge pull request #10 from StyraInc/inviter-link

docs: Update slack inviter link

Author: anderseknert

README.md

@@ -28,4 +28,4 @@ This requires `tectonic` to be installed (`brew install tectonic`).
 ## Community
 
 For questions, discussions and announcements related to Styra products, services and open source projects, please join
-the Styra community on [Slack](https://communityinviter.com/apps/styracommunity/signup)!
+the Styra community on [Slack](https://inviter.co/styra)!

assets/footer.md

@@ -3,4 +3,4 @@
 The Rego Cheat Sheet is maintained by [Styra](http://styra.com), the
 creators of OPA, and the Styra community. If you have any questions,
 suggestions, or would like to get involved, please join us on our
-[Slack](https://communityinviter.com/apps/styracommunity/signup).
+[Slack](https://inviter.co/styra).

assets/footer.tex

@@ -4,4 +4,4 @@
 the creators of OPA, and the Styra community.
 If you have any questions, suggestions, or would like to
 get involved, please join us on our
-\href{https://communityinviter.com/apps/styracommunity/signup}{Slack}.
+\href{https://inviter.co/styra}{Slack}.