Signing with own release keys

[AkashRajpurohit]

Firstly great walkthrough for setting up GitHub actions for flutter development.
I would like to point out one issue in it.

It works fine when you are releasing debug apk. So your build.gradle in /android/app/build.gradle on line 50

 release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }

is like this where you are using debug keys.

But for release it would be better to sign the apk with our signing keys and create a small release apk instead of debug apk.

Is there any option to do this configuration?