refactor: move firmware workspace under firmware

docs/src/sitl.md

@@ -11,6 +11,7 @@ It is a pre-bench software gate, not a physical-flight validation.
 ## Run the closed loop
 
 ```sh
+cd firmware
 docker compose -f tools/sitl/compose.yaml up -d --build
 tools/sitl/kaptan-sim ready
 tools/sitl/kaptan-sim move 5 3 1 --wait
@@ -21,6 +22,7 @@ docker compose -f tools/sitl/compose.yaml down
 For the reproducible command-path gate, use:
 
 ```sh
+cd firmware
 tools/sitl/e2e-smoke.sh
 ```