[Docs]: Incorrect advice about worker count on CircleCI

[glenjamin]

Page(s)

https://playwright.dev/docs/ci#circleci

Description

The docs currently say this:

Note: When using the docker agent definition, you are specifying the resource class of where playwright runs to the 'medium' tier here. The default behavior of Playwright is to set the number of workers to the detected core count (2 in the case of the medium tier). Overriding the number of workers to greater than this number will cause unnecessary timeouts and failures.

However when using the docker agent, the core count detects the host's core count, not the cores allocated to the container.

This post on the CircleCI discuss notes how the allocated core count can be detected: https://discuss.circleci.com/t/environment-variable-set-to-the-number-of-available-cpus/32670/4

But it might be simpler to advise people to set the core count explicitly