docs: document enable_discord_role_updates in Discord testing flow

Author: shubham5080

docs/TESTING_DISCORD.md

@@ -4,13 +4,18 @@ This guide explains how to safely validate Gitcord role automation in a Discord
 
 ## Recommended Test Sequence
 
-1. Keep `runtime.mode: "dry-run"` and `discord.permissions.write: false`.
+1. **Dry-run phase (no Discord role mutations):** In your config, set:
+   - `runtime.mode: "dry-run"`
+   - `runtime.enable_discord_role_updates: false`
+   - `discord.permissions.write: false`  
+   With `enable_discord_role_updates: false`, `run-once` will not apply Discord role add/remove even if mode or permissions were mis-set.
 2. Run a sync:
    - `./.venv/bin/python -m ghdcbot.cli --config config/my-org-config.yaml run-once`
 3. Review the generated report at `<data_dir>/reports/audit.md`.
 4. Verify planned role changes and identity mappings are correct.
-5. Enable live updates only after review:
+5. **Live phase (apply role updates):** Only after review, set:
    - `runtime.mode: "active"`
+   - `runtime.enable_discord_role_updates: true`
    - `discord.permissions.write: true`
 6. Run `run-once` again and confirm expected role changes in Discord.