yarn.lock is untracked when setting up a local copy of the project

Created by: lukyth

Is your proposal related to a problem?

Yes.

When I try to contribute to this project by following the instruction in https://github.com/facebook/create-react-app/blob/master/CONTRIBUTING.md#setting-up-a-local-copy

1. Clone the repo with git clone https://github.com/facebook/create-react-app
2. Run yarn in the root create-react-app folder.

yarn.lock will be generated and is untracked.

Right now yarn.lock is neither checked in nor ignored by .gitignore. So I have to get rid of it somehow (stash/remove) when I commit the code. If I remove it and run yarn again, it'll just generate a new one. This could become a bit frustrating.

Describe the solution you'd like

Checking in yarn.lock as well. I could take care of this if the idea is accepted.

Describe alternatives you've considered

Ignore yarn.lock in .gitignore. But I'd rather avoid that and check it in instead according to https://yarnpkg.com/lang/en/docs/yarn-lock/#toc-check-into-source-control

Additional context

None.