Expose project ID and update docs on triggering pipelines via CURL - how to obtain Project ID?

https://docs.gitlab.com/ee/ci/triggers/README.html#when-used-with-multi-project-pipelines

• curl --request POST --form "token=$CI_JOB_TOKEN" --form ref=master https://gitlab.example.com/api/v4/projects/9/trigger/pipeline

https://docs.gitlab.com/ee/ci/triggers/README.html#triggering-a-pipeline-from-a-webhook

https://gitlab.example.com/api/v4/projects/9/ref/master/trigger/pipeline?token=TOKEN

But how do I get the project ID? It's nowhere to be found in the UI.

And no, I don't wish to learn the API, and call API endpoint to list projects, then get my project ID, from my localhost curl. All I want is to copy-paste a curl command from the docs into my gitlab-ci.yml, and obtain the project ID in a dead easy way. Project ID is nowhere to be found in the UI or URLs.

1. Please expose Project ID somewhere in the UI so it's easily obtainable.
2. Please update the docs related to triggering pipelines from command line, and point us where project ID can be easily found.

CC @markglenfletcher @markpundsack @bikebilly