Removed doc based on new changes (#192)

Author: jef

README.md

@@ -26,7 +26,6 @@ When Git 2.18 or higher is not in your PATH, falls back to the REST API to downl
 - Fallback to REST API download
   - When Git 2.18 or higher is not in the PATH, the REST API will be used to download the files
   - When using a job container, the container's PATH is used
-- Removed input `submodules`
 
 Refer [here](https://github.com/actions/checkout/blob/v1/README.md) for previous versions.