misc: Update CONTRIBUTING.md for the monorepo changes

[krystofwoldrich]

#skip-changelog

[antonis]

l: Adding a note on a minor issue I encountered. I think the yarn run-android and yarn run-ios on the Run the emulators sections should be changed to yarn android and yarn ios to match the scripts of the samples.
I'll be glad to open a separate PR for this but thought of adding a note on this related PR 1st.

[lucas-zimerman]

I like the idea of both samples and main SDK having the same script name for running the ios/android samples, although, I usually don't use those commands (only yarn start) since the yarn run-android does nothing for me.