Improvement README.md for Android installation

[22starworld]

There is missing information about usage on android.
My suggestion :

For Android :

1. Install Termux.
2. Open Termux, for update latest packages, write pkg update press Enter and write pkg upgrade press Enter.
3. Access storage (for not rooted device), write termux-setup-storage press Enter.
4. Install apkeep, write pkg install apkeep press Enter.
5. Exemple internal storage : apkeep -a com.instagram.android storage/shared/, or google play
   apkeep -a com.instagram.android -d google-play -i ~/storage/shared/apkeep/config/AAS_token.ini storage/shared/apkeep/