docs: fix remaining hardcoded headlamp namespace to <your-namespace> placeholder

Prior commit was inconsistent — some files used <your-namespace> while
DEPLOYMENT.md, TROUBLESHOOTING.md and several troubleshooting/user-guide
docs still hardcoded headlamp as the namespace.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

docs/getting-started/prerequisites.md

@@ -112,7 +112,7 @@ The plugin requires permissions to access the Polaris dashboard via Kubernetes s
 ```bash
 # Test if Headlamp service account has permission
 kubectl auth can-i get services/proxy \
-  --as=system:serviceaccount:headlamp:headlamp \
+  --as=system:serviceaccount:<your-namespace>:headlamp \
   -n polaris \
   --resource-name=polaris-dashboard
 

docs/getting-started/quick-start.md

@@ -119,7 +119,7 @@ kubectl -n <your-namespace> exec -it deployment/headlamp -c headlamp -- \
 
 # Verify RBAC is correct
 kubectl auth can-i get services/proxy \
-  --as=system:serviceaccount:headlamp:headlamp \
+  --as=system:serviceaccount:<your-namespace>:headlamp \
   -n polaris \
   --resource-name=polaris-dashboard