Link to setup guide in WORKFLOW.md (#30708)

* Mention dev containers and WSL

* Update WORKFLOW.md

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Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>
old-commit-hash: fb977e45cd

docs/WORKFLOW.md

@@ -2,7 +2,7 @@
 
 Aside from the ML models, most tools used for openpilot development are in this repo.
 
-Most development happens on normal Ubuntu workstations, and not in cars or directly on comma devices.
+Most development happens on normal Ubuntu workstations, and not in cars or directly on comma devices. See the [setup guide](../tools) for getting your PC setup for openpilot development.
 
 ## Quick start