Adjust links on home page

Group links to GitHub together for clarity. Otherwise it suggests
that the issue tracker and pull requests are hosted separately.

Also tweak the link descriptions for the project mailing lists, so
that they better match the descriptions on the mailing list server.

Author: dpward

index.md

@@ -10,11 +10,11 @@ SSSD is a system daemon. Its primary function is to provide access to local or r
 
   - The primary resources to learn about SSSD or to get involved in its development are:
 
-    - [Home page](https://github.com/SSSD/sssd)
-    - [Bug tracker](https://github.com/SSSD/sssd/issues)
-    - [Mailing list for SSSD users discussion](https://lists.fedorahosted.org/admin/lists/sssd-users.lists.fedorahosted.org/)
-    - [Mailing list for SSSD development discussion](https://lists.fedorahosted.org/admin/lists/sssd-devel.lists.fedorahosted.org/)
-    - [GitHub pull requests](https://github.com/SSSD/sssd/pulls)
+    - [GitHub repository](https://github.com/SSSD/sssd)
+      - [Issues](https://github.com/SSSD/sssd/issues)
+      - [Pull requests](https://github.com/SSSD/sssd/pulls)
+    - [Mailing list for end-user discussions](https://lists.fedorahosted.org/admin/lists/sssd-users.lists.fedorahosted.org/)
+    - [Mailing list for development](https://lists.fedorahosted.org/admin/lists/sssd-devel.lists.fedorahosted.org/)
 
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