Remove mentions that decrypt_polling is broken

And add notice about bandwidth usage, related to https://github.com/iv-org/invidious/issues/3234

config/config.example.yml

@@ -349,8 +349,8 @@ feed_threads: 1
 ## Enable/Disable the polling job that keeps the decryption
 ## function (for "secured" videos) up to date.
 ##
-## Note: This part of the code is currently broken, so changing
-## this setting has no impact.
+## Note: This part of the code generate a small amount of data every minute.
+## This may not be desired if you have bandwidth limits set by your ISP.
 ##
 ## Accepted values: true, false
 ## Default: true