Enhancement: define mgs strings to send

[flames]

https://github.com/anhbh310/gotify2telegram/blob/master/plugin.go#L119
p.send_msg_to_telegram(msg.Date + "\n" + msg.Title + "\n\n" + msg.Message)

Please, add the possibility, to define (ENVs) what part of msg to send and to cut to lenght, like...
if 0, don't send at all, if int >0 cut string length to int.
TELEGRAM_MSG_DATE(int)
TELEGRAM_MSG_TITLE(int)
TELEGRAM_MSG_MESSAGE(int)

thanks in advance!