Add quickstart for prometheus.

[genchilu]

Related issue

I add an quickstart for Prometheus, and add want to add it to 5min-tutorial.

I also create another PR for doc.

Proposed changes

Checklist

• I have read the contributing guidelines
• I have read the security policy
• I confirm that this pull request does not address a security vulnerability. If this pull request addresses a security
  vulnerability, I confirm that I got green light (please contact security@ory.sh) from the maintainers to push the changes.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation within the code base (if appropriate)
• I have documented my changes in the developer guide (if appropriate)

Further comments

[aeneasr]

Awesome, thank you! :)