Add info about submodules to the README.md

README.md

@@ -10,6 +10,17 @@ XDA threads:
 * mako: http://forum.xda-developers.com/showthread.php?p=46223377
 * hammerhead: http://forum.xda-developers.com/showthread.php?t=2571011
 
+###Sources
+MultiROM uses git submodules, so you need to clone them as well:
+
+    git clone https://github.com/Tasssadar/multirom.git system/extras/multirom
+    cd system/extras/multirom
+    git submodule update --init
+
+It also needs libbootimg:
+
+    git clone https://github.com/Tasssadar/libbootimg.git system/extras/libbootimg
+
 ###Build
 Clone repo to folder `system/extras/multirom` inside Android 4.x source tree.
 You can find device folders on my github, I currently use OmniROM tree for