Added 10 courses on Android (#5041)

* Update free-courses-en.md

Added 4 more free courses for Android.

* Update free-courses-en.md

Added 4 free courses for Android

* Update free-courses-en.md

Added 10 courses on Android

* Update free-courses-en.md

Added 10 courses on Android

free-courses-en.md

@@ -87,22 +87,32 @@
 
 ### Android
 
+* [Advanced Android App Development](https://www.udacity.com/course/advanced-android-app-development--ud855) - (Udacity)
+* [Advanced Android with Kotlin](https://www.udacity.com/course/advanced-android-with-kotlin--ud940) - (Udacity)
 * [Android App Development for Beginners Playlist](https://www.youtube.com/playlist?list=PL6gx4Cwl9DGBsvRxJJOzG4r4k_zLKrnxl) - Bucky Roberts - (thenewboston)
+* [Android Basics: Data Storage](https://www.udacity.com/course/android-basics-data-storage--ud845) - (Udacity)
+* [Android Basics: Multiscreen Apps](https://www.udacity.com/course/android-basics-multiscreen-apps--ud839) - (Udacity)
+* [Android Basics: Networking](https://www.udacity.com/course/android-basics-networking--ud843) - (Udacity)
+* [Android Basics: User Input](https://www.udacity.com/course/android-basics-user-input--ud836) - (Udacity)
+* [Android Basics: User Interface](https://www.udacity.com/course/android-basics-user-interface--ud834) - (Udacity)
 * [Android Developer Fundamentals (Version 2) — Codelab](https://developer.android.com/courses/fundamentals-training/toc-v2)
 * [Android Developer Fundamentals (Version 2) — Concepts](https://google-developer-training.github.io/android-developer-fundamentals-course-concepts-v2/index.html)
+* [Android Performance](https://www.udacity.com/course/android-performance--ud825) - (Udacity)
+* [Build Native Mobile Apps with Flutter](https://www.udacity.com/course/build-native-mobile-apps-with-flutter--ud905) - (Udacity)
 * [CS50 2019 - Android Track](https://www.youtube.com/playlist?list=PLhQjrBD2T381qULidYDKP55-4u1piASC1) - David J. Malan (Harvard OpenCourseWare)
+* [Developing Android Apps](https://www.udacity.com/course/new-android-fundamentals--ud851) - (Udacity)
+* [Developing Android Apps with Kotlin](https://www.udacity.com/course/developing-android-apps-with-kotlin--ud9012) - (Udacity)
+* [Firebase in a Weekend: Android](https://www.udacity.com/course/firebase-in-a-weekend-by-google-android--ud0352) - (Udacity)
+* [Gradle for Android and Java](https://www.udacity.com/course/gradle-for-android-and-java--ud867) - (Udacity)
+* [Kotlin Bootcamp for Programmers](https://www.udacity.com/course/kotlin-bootcamp-for-programmers--ud9011) - (Udacity)
 * [Learn how to program: Android](https://www.learnhowtoprogram.com/android) - Epicodus Inc.
 * [Material design](https://material.io/guidelines/)
+* [Material Design for Android Developers](https://www.udacity.com/course/material-design-for-android-developers--ud862) - (Udacity)
 * [Programming Cloud Services for Android Handheld Systems](https://www.coursera.org/course/mobilecloudprogram)
 * [Programming Mobile Applications for Android Handheld Systems pt. 1](https://www.coursera.org/course/android)
 * [Programming Mobile Applications for Android Handheld Systems pt. 2](https://www.coursera.org/course/androidpart2)
 * [Programming Mobile Services for Android Handheld Systems: Communication](https://www.coursera.org/course/posacommunication)
 * [Programming Mobile Services for Android Handheld Systems: Concurrency](https://www.coursera.org/course/posaconcurrency)
-* [Udacity Android Basics: Data Storage](https://www.udacity.com/course/android-basics-data-storage--ud845)
-* [Udacity Android Basics: Multiscreen Apps](https://www.udacity.com/course/android-basics-multiscreen-apps--ud839)
-* [Udacity Android Basics: Networking](https://www.udacity.com/course/android-basics-networking--ud843)
-* [Udacity Android Basics: User Input](https://www.udacity.com/course/android-basics-user-input--ud836)
-* [Udacity Android Basics: User Interface](https://www.udacity.com/course/android-basics-user-interface--ud834)
 
 
 ### Angular