Removed out-dated advice to use non-existing OST binaries

modules/doc/install.rst

 Installing OpenStructure From Source
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-.. note::
-
-  This document describes how to install OpenStructure from source. If you are
-  mainly insterested in using OpenStructure and are not planning to modify the
-  code of OpenStructure itself, please use one of the binaries `available for
-  download <http://www.openstructure.org/download/>`_.
-  
-
 Brief Overview
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