README: We don't use submodules any longer

Author: gollux

README.md

@@ -32,16 +32,6 @@ main branch, is intended for developers and everyone interested in
 contributing or just curious to see how the code works and wanting to
 hack on it.
 
-Please note that since the sandbox is contained in a
-[git submodule](http://git-scm.com/docs/git-submodule) you should append
-`--recursive` to the standard `git clone` command to obtain it. Or, if
-you have already cloned CMS, simply run the following command from
-inside the repository:
-
-```bash
-git submodule update --init
-```
-
 
 Support
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