Add comment "For Robolectric".

Change-Id: I85f9d6c4609e952243cede64ee50d7b857ce14ce

build-logic/convention/src/main/kotlin/com/google/samples/apps/nowinandroid/TestOptions.kt

@@ -24,6 +24,7 @@ internal fun Project.configureTestOptions(
 ) {
     commonExtension.apply {
         testOptions {
+            // For Robolectric
             unitTests {
                 isIncludeAndroidResources = true
             }