updates readme with additional infos for expansion files

adds the info that the mp4 files inside expansion files have not to be compressed to get it working

README.md

@@ -195,7 +195,12 @@ var styles = StyleSheet.create({
 - * *For iOS you also need to specify muted for this to work*
 
 ## Android Expansion File Usage
-Only supports .mp4 files
+Only supports .mp4 files.
+The video files have not to be compressed.
+Linux command example to exclude .mp4 files from zip compression:
+```bash
+zip -r -n.mp4 *.mp4 main.1.com.exmample.com
+```
 ```javascript
 // Within your render function, assuming you have a file called
 // "background.mp4" in your expansion file. Just add your main and (if applicable) patch version