id: add examples (#19800)

Author: Managor

pages/common/id.md

@@ -23,6 +23,14 @@
 
 `id {{[-g|--group]}}`
 
+- Display all groups the current user belongs to:
+
+`id {{[-Gn|--groups --name]}}`
+
 - Display an arbitrary user's ID (UID), group ID (GID) and groups to which they belong:
 
 `id {{username}}`
+
+- Skip name lookup and specify the UID number explicitly:
+
+`id +{{uid_number}}`