Update README.md

README.md

-# MMR
-
 ## Installation
     git clone --recursive https://github.com/didibib/multimedia-retrieval.git
     git submodule update --init --recursive
 
+If a .zip file is downloaded then do:
+    
+    git submodule update --init --recursive    
+
 Configure and build:
 
     Couble click the `build.bat`. It will build for VS22 x64.