Add information on the Fedora Join channels

This is part of our attempt to make Fedora Join more visible to
newcomers. It was discussed with Mindshare here:
https://pagure.io/mindshare/issue/147

A blog post will be out on the community blog in a few days. Preview
link:
https://communityblog.fedoraproject.org/?p=8223&preview=1&_ppp=0fa8698e28

An e-mail to the Join SIG mailing list about this can be seen here:
https://lists.fedoraproject.org/archives/list/fedora-join@lists.fedoraproject.org/thread/V6HDQZGM5YUCJDYIRCMJKT4TLKRE3ZVA/

project/modules/ROOT/pages/join.adoc

@@ -1,9 +1,16 @@
-[NOTE]
-====
-This page is a placeholder. It should have content adopted from
-https://fedoraproject.org/wiki/Join
+Get involved
+=============
 
-You can help make this document more useful by
-submitting changes via pull request at https://pagure.io/Fedora-Council/council-docs
+The Fedora community consists of people all over the world that come together to develop software and content to promote the philosophy of Free and Open Source Software (FOSS).
+Fedora is a xref:orgchart.adoc[massive organisation], and people carry out https://fedoraproject.org/wiki/Join[different roles] to keep the community ticking along.
 
-====
+So, the best way of getting involved is speaking to the people of Fedora!
+The https://fedoraproject.org/wiki/SIGs/Join[Fedora Join Special Interest Group (SIG)] maintains channels where community you can speak to community members and learn more about Fedora---the community and its workings:
+
+- Email: https://lists.fedoraproject.org/admin/lists/fedora-join@lists.fedoraproject.org/[Fedora Join mailing list].
+- Chat (over IRC): https://webchat.freenode.net/?channels=#fedora-join[#fedora-join on Freenode.net].
+- Chat (over Telegram): https://t.me/joinfedora[Fedora Join Telegram group].
+
+
+All the infrastructure used by the Fedora community is linked to a Fedora account.
+You can get one https://admin.fedoraproject.org/accounts/user/new[here].