How to update Galaxy Ace GT-S5839i to Android 2.3.6 BULL1 latest firmware

Android 2.3.6 for Galaxy Ace GT-S5839i was recently released in December for several countries and some subscribing companies. The update is available for Czech Republic (Vodafone), Germany (Vodafone), Spain (Vodafone), Italy (Vodafone) and France (SFR) and contains the improved Android 2.3.6 that fixes some bugs and …