Merge pull request #35271 from Expensify/blimpich-patch-1

[No QA] Update README.md to include instructions on installing Xcode tools

README.md

@@ -58,6 +58,7 @@ If you're using another operating system, you will need to ensure `mkcert` is in
 ## Running the iOS app 📱
 For an M1 Mac, read this [SO](https://stackoverflow.com/questions/64901180/how-to-run-cocoapods-on-apple-silicon-m1) for installing cocoapods.
 
+* If you haven't already, install Xcode tools and make sure to install the optional "iOS Platform" package as well. This installation may take awhile.
 * Install project gems, including cocoapods, using bundler to ensure everyone uses the same versions. In the project root, run: `bundle install`
     * If you get the error `Could not find 'bundler'`, install the bundler gem first: `gem install bundler` and try again.
     * If you are using MacOS and get the error `Gem::FilePermissionError` when trying to install the bundler gem, you're likely using system Ruby, which requires administrator permission to modify. To get around this, install another version of Ruby with a version manager like [rbenv](https://github.com/rbenv/rbenv#installation).