consider adding a CONTRIBUTING file

[marandaneto]

similar to https://github.com/getsentry/sentry-java/blob/main/CONTRIBUTING.md and other SDKs
so we know which command to build and run locally in case we want to debug/test it

commands that should be there:
yarn install
yarn build

and ideally which folder outputs the executable

[BYK]

I think we can just yank this section: https://github.com/getsentry/craft?tab=readme-ov-file#development into a new file, add an "Installation" section at the top saying:

yarn install
yarn build

Or something close and get this done.