feat: Add a health check endpoint

[Xusifob]

Hello everyone;

I am currently using a mercure server on AWS and would like to add a health check so that if the server does not reply it can be shut down and rebuilt automatically.

I can not use the /.well-known/mercure endpoint as I am using authentification to access the topics.

Would it be possible to access a /.well-known/health_check that returns a HTTP 200 with some information about the server's health.

[cvergne]

👋 I think it's missing in the documentation, but there is already an healthcheck endpoint on /healthz which returns an empty HTTP 200.

[Xusifob]

Thanks for the reply

Is there a repository with documentation so I can update it ? I did not find any

[dunglas]

The documentation is in this repo: https://github.com/dunglas/mercure/tree/main/docs

[maxhelias]

PR is open #891