improved README

see #129

README.md

@@ -38,6 +38,8 @@ services:
 
 [signal-cli](https://github.com/AsamK/signal-cli), which this REST API wrapper is based on, recommends to call `receive` on a regular basis. So, if you are not already calling the `receive` endpoint regularily, it is recommended to set the `AUTO_RECEIVE_SCHEDULE` parameter in the docker-compose.yml file. The `AUTO_RECEIVE_SCHEDULE` accepts cron schedule expressions and automatically calls the `receive` endpoint at the given time. e.g: `0 22 * * *` calls `receive` daily at 10pm. If you are not familiar with cron schedule expressions, you can use this [website](https://crontab.guru).
 
+**WARNING** Calling `receive` will fetch all the messages for the registered Signal number from the Signal Server! So, if you are using the REST API for receiving messages, it's _not_ a good idea to use the `AUTO_RECEIVE_SCHEDULE` parameter, as you might lose some messages that way.
+
 
 ## Native Image (EXPERIMENTAL)