Update Limitations-&-Common-Issues.md

docs/Limitations-&-Common-Issues.md

+# Limitations and Common Issues
+
 ## Unity SDK
 ### Headless Mode
 Currently headless mode is disabled. We hope to address these in a future version of Unity.
 
 If you receive an exception `"Couldn't launch new environment because communication port {} is still in use. "`, you can change the worker number in the python script when calling 
 
-`UnityEnvironment(file_name=filename, worker_num=X)`
+`UnityEnvironment(file_name=filename, worker_num=X)`