Improve Documentation v4.1

[validcube]

Description

There are some things that I didn't like with the original improvements I've made (these are my problem, crazy)

• Clarify SHA-256 Hashes
  • Previously, it says that the App's SHA-256 must match the table but does not specify that it's for verifying app's certificate.
• Fix Obtainium link for development listing
  • Previously, the Obtainium link for getting development listing was using the outdated configuration. It grab the development APK if the APK is app.lawnchair.debug which is not the case as of now with app.lawnchair.nightly
  • Could potentially also update the upstream configuration for Lawnchair @ https://github.com/ImranR98/apps.obtainium.imranr.dev
• Lawnchair as distribution market - 054ca70
• Flowerpot
  • Fix Flowerpot crawlers
  • Merge Flowerpot crawlers' result with an existing list of Flowerpot
  • How to assign apps to categories
• Reinstate Python script to update Google Fonts listing from Update Google Fonts listing #4362 to fix [FEATURE] (Online) Google Fonts listings #5196
  • Previously, it was removed because the script isn't tested for CI environment, and not enough time available to possibly complete it within the next beta version of Lawnchair
  • Test it in CI environment
  • Update the documentation that it should be done ad-hoc, as needed basis

There seems to be a recurring theme where I leak my API key every year.

Type of change

✅ General change (non-breaking change that doesn't fit the below categories like copyediting)
❌ Bug fix (non-breaking change which fixes an issue)
✅ New feature (non-breaking change which adds functionality)
❌ Breaking change (fix or feature that would cause existing functionality to not work as expected)