Fix README new directory location cwlref-runner

Author: johnbradley

README.rst

@@ -29,7 +29,7 @@ Or from source::
 
   git clone https://github.com/common-workflow-language/cwltool.git
   cd cwltool && python setup.py install
-  cd cwl-runner && python setup.py install
+  cd cwlref-runner && python setup.py install
 
 Run on the command line
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