Update dev's documentation for enabling webhooks on self-hosted

[BOHEUS]

Based on conversation in Discord server https://discord.com/channels/1130383047699738754/1276587741144154193

Right now, there's no documentation regarding enabling webhooks on self-hosted. As it turned out, a new docker instance and change in .env variables are needed in order to send webhooks. Please create a new page or update an existing one with all information required to run the worker responsible for sending webhooks.

Summary:

• instead of using Postgres, Redis must be used (thus new container)
• in .env MESSAGE_QUEUE_TYPE=bull-mq, REDIS_HOST=127.0.0.1, REDIS_PORT=6379
• npx nx twenty-server:worker must be running in parallel to npx nx start or npx nx twenty-server:start

Ideally, another command similar to make postgres-on-docker or make postgres-on-linux should be added to make transition easier (and also a way of controlling it for non-tech people)

[skyfox675]

@charlesBochet I can take a run at the doc updates if you like

@BOHEUS, I missed the worker for the first view months of running Twenty 😂, @LumosViridi is finishing up a follow-on to #6356 for the worker container and storage changes. But, we're still running with MESSAGE_QUEUE_TYPE=pg-boss with webhooks working. I think Redis is the path forward but this is working as of v0.23.2

[Bonapara]

Thanks to you both! @charlesBochet is going to update it as he updates the system :)