todo: update cordova Android docs

[mesqueeb]

Just leaving some notes for myself of parts of the documentation I want to update in the near future.

[mesqueeb]

Update the method of signing an android app with info from & link to latest docs: signing-an-app

It's much easier to just add the keystore paths in build.json, and cordova takes care of the rest. You need to do nothing else.

[mesqueeb]

(both iOS and Android)

Write something at the top about the importance of first doing "Create your first Cordova app" from the cordova documentation. & Follow the cordova documentation on the "installing the requirements" of both iOS and Android.

Once you are able to successfully build & launch the first cordova app on your phone and/or in a simulator, then come back to Quasar and follow the rest of this guide on how to add cordova to your Quasar app.

This way it's easier to separate concerns and if you encounter any problems it's easier to know if it's related to just your first Cordova app, or if it's specifically related to your Quasar App.