Simplify clone instructions

Author: rpdelaney

README.rst

@@ -22,10 +22,7 @@ a clone does not do this automatically:
 
 ::
 
-    git clone git@github.com:rpdelaney/python-chess-annotator.git
-    cd python-chess-annotator/annotator/
-    git submodule init eco
-    git submodule update eco
+    git clone --recurse-submodules git@github.com:rpdelaney/python-chess-annotator.git
 
 Dependencies
 ------------