Quick Start docs and fastlane command need improving to handle case where no apk has been manually uploaded yet

[lukehutch]

New Issue Checklist

• Updated fastlane to the latest version
• I read the Contribution Guidelines
• I read docs.fastlane.tools
• I searched for existing GitHub issues

Issue Description

This doc page says under "Quick Start":

Before using supply to connect to Google Play Store, you'll need to set up your app manually first by uploading at least one build to Google Play Store. See fastlane/fastlane#14686 for more info.

That issue doesn't have enough info to help people solve the problem.

Manually uploading an APK just to get Fastlane working is a huge blocker step, so the docs need some more details here about exactly what steps to go through to accomplish this.

If you haven't manually uploaded an apk yet, then the command suggested under the quoted text above, fastlane supply, gives: [!] Google Api Error: Invalid request - Package not found: <packagename>, as does fastlane init before that:

[02:48:36]: Google Api Error: Invalid request - Package not found: <packagename>.
[02:48:36]: Setting up `supply` (metadata management action) failed, but don't worry, you can try setting it up again using `fastlane supply init` whenever you want.

Furthermore, the user should not have to google to figure out what the problem is, when they see errors like the following. Fastlane needs to detect this and explain exactly what the user needs to do, since this will be such a common problem:

[carol1987g]

Hello, MyAARPMedicare] @lukehutch

To resolve the Fastlane supply setup issue for Google Play Store, follow these steps:

Create Service Account: Set up a Google Developers Service Account.
Enable Google Play API: Enable the Google Play Developer API in your Google Cloud Project.
Generate JSON Key: Create a new service account key in JSON format and save it on your computer.
Upload Build Manually: Before using fastlane supply, manually upload at least one build (APK or AAB) to the Google Play Store.
Initialize Fastlane: Run fastlane supply init in your project folder after the manual upload.

This solution will resolve your issue.

Thanks & Best Regards
carol1987g