Document best practices on Android

[peitschie]

Spawned from discussion on #963

The best approaches found on Android are:

1. Use autoConnect and don't explicitly scan (i.e., let the OS schedule this itself)
2. Explicitly scan and then use connect
3. (Maybe) for a non-bonded device, it's safe to just use connect without an explicit scan (to be confirmed)

Additional things worth documenting:

1. Permission flows and differences per Android version
2. Location services & impacts on scanning
3. Background processing
4. Impacts of scan latency settings (https://github.com/don/cordova-plugin-ble-central/issues/959)
5. Use of neverForLocation on Android 12+
6. Android disconnect supervision timeouts, and why rapid reconnects can often fail

Documenting the known caveats and quirks would help implementors more effectively use this plugin.