Deduplicate and improve development docs

[mrsarm]

We have documented the branding and signing process here in the official docs and here in the README. Moreover, the text are not exactly the same.

We should:

• Merge/move all the development guides from the README to the community docs
• Only leaves links in the README of where in the community docs find how compiling and branding the app.
• Improve the section with the development tools required. E.g.:
  • This post a user was confused about base16.
  • The section mention as requirement the keytool that is already part of any Java distribution mentioned in the first item (BTW the Java 11 should also be replaced by Java 11+ because the SDK takes care of lowering the targeted Java version when compiling).
  • The make command is also required
• Fix target name keyprint-aab → keyprint-bundle in https://docs.communityhealthtoolkit.org/apps/tutorials/android-wrapper/#2-building-the-apk-and-aab-files.

[mrsarm]

Implemented in both PRs mentioned above.