acknowledge contributors too

Author: mr-c

README.rst

@@ -85,7 +85,7 @@ The ``cwlref-runner`` package is optional and provides an additional entry point
 under the alias ``cwl-runner``, which is the implementation-agnostic name for the
 default CWL interpreter installed on a host.
 
-``cwltool`` is provided by the CWL project, `a member project of Software Freedom Conservancy <https://sfconservancy.org/news/2018/apr/11/cwl-new-member-project/>`_
+``cwltool`` is provided by the CWL project, `a member project of Software Freedom Conservancy <https://sfconservancy.org/news/2018/apr/11/cwl-new-member-project/>`_ and our `many contributors <https://github.com/common-workflow-language/cwltool/graphs/contributors>`_.
 
 Install
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