Documentation: Update README.md with Note about Android Studio/Xcode

[SiobhyB]

This PR updates the README.md with a reference to React Native's documentation, which details configurations that are needed in Android Studio and Xcode in order for the demo apps to run.

Fixes #3062

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered if this change warrants user-facing release notes more info and have added them to RELEASE-NOTES.txt if necessary.

[dcalhoun]

This looks good! 💯 Thanks for adding clarity to the setup documentation. I offered one small suggestion related to punctuation.

[peril-wordpress-mobile]

Wanna run full suite of Android and iOS UI tests? Click here and 'Approve' CI job!

[hypest]

Thanks for the PR Siobhan!

I think it will be useful for others (as well as our future selves) to know what were the issues you did encounter the the now added documentation solves. Do you think we could add some brief descriptions of the issues and what helped fixing them, either in the PR description here or in the original GitHub ticket?

We could also assess how "popular" those issues can be and actually go ahead and mention them in the README directly, in the Troubleshooting section for example.

[SiobhyB]

@hypest, sure! I don't recall all of the errors but, with Android Studio, the emulator didn't originally work because I hadn't added the needed lines to my $HOME/.bash_profile and then the app wouldn't load due to the version of JDK I was running. This was the error that helped me figure out there was a conflict with my JDK version:

Could not initialize class org.codehaus.groovy.runtime.InvokerHelper

With Xcode, there was some kind of conflict with the way Ruby's installed on my machine. I kept getting the following error and this guide helped me:

You don't have write permissions for the /Library/Ruby/Gems/2.6.0 directory

React Native's documentation is pretty comprehensive when it comes to how both Android Studio and Xcode should be set up, so I suspect being pointed towards it would have been enough for me to avoid the above errors. I ended up wading through a sea of StackOverflow posts when, in fact, the documentation had everything I needed, I just wasn't aware of it.

I've added some extra details to the troubleshooting section, let me know what you think!

[hypest]

... but, with Android Studio, the emulator didn't originally work because I hadn't added the needed lines to my $HOME/.bash_profile and then the app wouldn't load due to the version of JDK I was running.

and

I ended up wading through a sea of StackOverflow posts when, in fact, the documentation had everything I needed, I just wasn't aware of it.

Ah, I see. Yeah, unfortunately, there's no "single" way to setup things (one could use the Oracle provided JDK for example, not the OpenJDK from homebrew on Macos), and it one way or the other might conflict with WPAndroid's setup. I feel like being too prescriptive might do harm so, these kind of errors are probably best be left out of the "requirements" for gutenberg-mobile. That said, hinting about things in the Troubleshooting section is fair and helpful.

[hypest]

Looks good to me at this stage! I took the liberty to re-trigger the failed CI jobs as those seemed like flakiness fails. I'll LGTM when they get green!

[hypest]

LGTM!

[hypest]

All green, reviews are 👍, and since there's no assignee set to govern who merges, I'll go ahead and merge at this point (internal ref p9ugOq-Kc-p2).

[SiobhyB]

Excellent, thank you! :)