docs: fix quickstart plan/apply command signatures

Update docs/quickstart.md to use correct CLI command signatures:
- Replace 'cleveragents plan --project' with 'cleveragents plan use <action> --project'
- Replace 'cleveragents apply --project' with 'cleveragents plan list' + 'cleveragents plan apply <plan-id>'

Addresses reviewer non-blocking suggestion to verify CLI commands match
actual signatures before merging.

docs/quickstart.md

@@ -32,10 +32,12 @@ Create a resource file under `resources/` (example YAML) and register it with th
 ## Plan and apply
 
 ```bash
-# Generate a plan
-cleveragents plan --project my-project
-# Review the plan, then apply
-cleveragents apply --project my-project
+# Create a plan using an action on your project
+cleveragents plan use <action-name> --project my-project
+# List plans to find the plan ID
+cleveragents plan list
+# Review the plan, then apply it by plan ID
+cleveragents plan apply <plan-id>
 ```
 
 ## Troubleshooting