Alert URL in config.yaml?

I found this on the first line of the config file, what is it?
Searching I did not find any information, if I install from scratch this line is not present …

ALERTS_URL: https://download.chia.net/notify/mainnet_alert.txt

CHIA_ALERTS_PUBKEY: 89b7fd87cb56e926ecefb879a29aae308be01f31980569f6…