[v10.4.x] Typo fix in User API doc example (#86821)

Co-authored-by: Jack Baldry <jack.baldry@grafana.com>
Co-authored-by: nextMJ <77353838+nextMJ@users.noreply.github.com>
fix in User API doc example (#81890)

docs/sources/developers/http_api/user.md

@@ -66,7 +66,7 @@ Content-Type: application/json
     "isAdmin": true,
     "isDisabled": false,
     "lastSeenAt": "2020-04-10T20:29:27+03:00",
-    "lastSeenAtAge': "2m",
+    "lastSeenAtAge": "2m",
     "authLabels": ["OAuth"]
   },
   {