Document need to stop before config change

The applications to stop are loaded into pm2 from the configuration file provided by the source collection. If the source collection changes, the previous config file becomes unaccessible and pm2 cannot stop the previous application, thus preventing the new one from starting

Author: MattiSG

README.md

@@ -82,6 +82,10 @@ all:
       ota_directory: demo
 ```
 
+#### Changes on a existing deployment
+
+If the `ota_source_repository` is changed on an existing target, the application has to be [stopped](#playbook-execution-refinement) before the new configuration is deployed.
+
 - ### PM2 Configuration File — `pm2.config.cjs`
 
 **This file is mandatory**