Create "Release for Stores" instruction/guide

[nikaluus]

Describes the steps for creating a new release for stores.

Steps for uploading apk to play store:

use ionic package build android--profile prod --release --prod
...
Profit!
Steps for uploading ipa to app store:

use ionic package build ios --profile prod --release --prod
start Applicatoin Loader on MacOS
doubleclick on big gray "A" icon and select .ipa
if reuploading same version: add a incrementing second version number in config.xml: https://cordova.apache.org/docs/en/4.0.0/config_ref/index.html#additional-versioning