Update README.md

README.md

@@ -33,7 +33,9 @@ This project is based on [Open Camera](https://opencamera.org.uk/)  —  a popul
 ### Remote recording
 
 - **Connect** smartphone to the same network as PC
-- Use scripts provided in ```./api_client/``` directory to **send requests** for the application
+- Use scripts provided in ```./api_client/``` directory to **send requests** for the application.
+    - *Note: phase, which is returned by* ```start_recording``` *method, can be used to perform synchronization with external devices*
+ ![remote control methods](https://www.websequencediagrams.com/files/render?link=6txhpHrdgaebT4DYz2C3SaEQjHM1esYDkJZJvPZcgCJHbRAg3c8hqcJYgOmGirze)
 
 ## Good practices for data recording