Example showing how to name APK files with the version and build number. This goes in the `android.buildTypes` block.

app_build.gradle

buildTypes {
        applicationVariants.all { variant ->
            def version = "${variant.versionName}-${variant.versionCode}"

            variant.outputs.all { output ->
                if (variant.buildType.name == "debug") {
                    outputFileName = "AppName-debug-${version}.apk"
                } else if (variant.buildType.name == "staging") {
                    outputFileName = "AppName-staging-${version}.apk"
                } else if (variant.buildType.name == "release") {
                    outputFileName = "AppName-production-${version}.apk"
                }
            }
        }

...

}