docs: document --format md|html for Mermaid exports

Author: jeremi

orchestrator/USER_GUIDE.md

@@ -241,13 +241,15 @@ inspection or embedding in docs (GitHub renders Mermaid in Markdown).
 ```bash
 python -m orchestrator.main doctor graph --recipe odoo_create_or_update_module
 # writes: orchestrator/artifacts/graph/recipe_odoo_create_or_update_module.mmd
+# formats: add --format md or --format html to emit Markdown or a self-contained HTML viewer
 ```
 
 - Executed run graph (colored by node status):
 
 ```bash
 python -m orchestrator.main doctor run-graph --run-id <run_id> --recipe odoo_create_or_update_module
 # writes: orchestrator/artifacts/<task-id>/graph/run_<run_id>.mmd (+ JSON index)
+# formats: add --format md or --format html for Markdown/HTML
 ```
 
 Mermaid example (executed run):