[v10.3.x] TeamSync: Fix auth proxy docs on teamsync (#82877)

TeamSync: Fix auth proxy docs on teamsync (#82457)

fix auth proxy docs on teamsync

(cherry picked from commit 901e1b1865)

Co-authored-by: Jo <joao.guerreiro@grafana.com>

docs/sources/setup-grafana/configure-security/configure-authentication/auth-proxy/index.md

@@ -252,7 +252,7 @@ Once that's done. You can verify your mappings by querying the API.
 
 ```bash
 # First, inspect your teams and obtain the corresponding ID of the team we want to inspect the groups for.
-curl -H "X-WEBAUTH-USER: admin" http://localhost:3000/api/teams/search
+curl -H "X-WEBAUTH-USER: admin" -H "X-WEBAUTH-GROUPS: lokiteamOnExternalSystem" http://localhost:3000/api/teams/search
 {
   "totalCount": 2,
   "teams": [
@@ -280,7 +280,7 @@ curl -H "X-WEBAUTH-USER: admin" http://localhost:3000/api/teams/search
 }
 
 # Then, query the groups for that particular team. In our case, the Loki team which has an ID of "2".
-curl -H "X-WEBAUTH-USER: admin" http://localhost:3000/api/teams/2/groups
+curl -H "X-WEBAUTH-USER: admin" -H "X-WEBAUTH-GROUPS: lokiteamOnExternalSystem" http://localhost:3000/api/teams/2/groups
 [
   {
     "orgId": 1,
@@ -304,6 +304,10 @@ curl -H "X-WEBAUTH-USER: leonard" -H "X-WEBAUTH-GROUPS: lokiteamOnExternalSystem
 
 With this, the user `leonard` will be automatically placed into the Loki team as part of Grafana authentication.
 
+{{% admonition type="note" %}}
+An empty `X-WEBAUTH-GROUPS` or the absence of a groups header will remove the user from all teams.
+{{% /admonition %}}
+
 [Learn more about Team Sync]({{< relref "../../configure-team-sync" >}})
 
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