Update README.md

adding description to show how to update submodules to latest revision

README.md

@@ -105,6 +105,14 @@ If the build pass correctly without errors, you can go into build/bin/
 and run noggit. Note that `make install` will probably work but is not
 tested, and nobody has built distributable packages in years.
 
+# SUBMODULES #
+
+To pull the latest version of submodules use the following command at the root directory.
+
+```bash
+git submodule update --recursive --remote
+```
+
 # DEVELOPMENT #
 Feel free to ask the owner of the official repository
 (https://github.com/wowdev/noggit3) for write access or