Update stop_sign_urban_intersection_3c.json

[SHITIANYU-hue]

When I run :

python baseline_agent.py --config /home/tianyushi/code/macadgym/src/macad_gym/envs/intersection/stop_sign_urban_intersection_3c.json

in the path: /home/tianyushi/code/macad-agents/src/macad_agents

I found some configurations are missing in this jason file.

[praveen-palanisamy]

@SHITIANYU-hue , you can make the changes and update this PR by pushing to the same branch (SHITIANYU-hue:patch-1)