Using discord webhooks

1. Generate a webhook url for your discord server in your discord's server settings.

2. Set the environment variable with the unique token at the end of the discord webhook url example: https://discord.com/api/webhooks/1234567890/abcde

send discord messages with docker run:

-e DISCORD_WEBHOOK_URL="https://discord.com/api/webhooks/1234567890/abcde" \
-e DISCORD_PRE_UPDATE_BOOT_MESSAGE="Server is updating..." \

send discord messages with docker compose:

- DISCORD_WEBHOOK_URL=https://discord.com/api/webhooks/1234567890/abcde
- DISCORD_PRE_UPDATE_BOOT_MESSAGE=Server is updating...