Document COPR groups in the groups documentation

Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>

groups_in_fedora.md

@@ -20,6 +20,9 @@ With this trust comes a few "priviledges" such as:
  - Access to fedorapeople.org
  - Possibility to vote on some of the elections (including FESCo and the Council)
 
+These groups are also the ones used when one wants to share the maintenance of
+COPR projects with other people via a group.
+
 * Shell groups
 These groups are used when contributors gain access to some of the machines
 in the Fedora Infrastructure.
@@ -43,6 +46,13 @@ https://pagure.io/fedora-infrastructure/
 It is unlikely you will need to create "shell" group, but you can ask for the
 creation of a "tracking" or "pkgdb" group.
 
+
+### COPR groups
+
+COPR supports giving access to project based on group membership. These groups
+are regular ``tracking`` groups.
+
+
 ### "pkgdb" groups name
 
 In the days where pkgdb was an application in addition to a type of group, groups
@@ -53,6 +63,7 @@ names.
 
 **When requesting a "pkgdb" group, please try to adhere to this standard.**
 
+
 ### "pkgdb" groups and mailing list
 
 "pkgdb" groups are created to maintain packages. They are meant to be CC'ed on