remove git clone instruction from README

This instruction assumes that the user has SSH keys set up, and is
not cloning from a fork. It is also incorrect without a `cd ocfweb`
afterwards. In any case "Clone the repo" in the previous sentence
should be sufficient.

README.md

@@ -17,7 +17,6 @@ development mode with minimal extra setup.
 
 Clone the repo, and be sure to check out submodules:
 
-    $ git clone git@github.com:ocf/ocfweb.git
     $ git submodule update --init
     $ make install-hooks