mention in README the inclusion of morse project files

I checked. They are intact since being added, so we don't need to add
extra copyright notices in them.

README.rst

@@ -87,12 +87,18 @@ type ``make html`` instead of ``make latexpdf``.
 Comments
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+* the `cmake` folder contains files extracted from
+  https://gitlab.inria.fr/solverstack/morse_cmake, a separate project licensed
+  under the "CeCILL-C" license, please see
+  http://www.cecill.info/licences/Licence_CeCILL-C_V1-en.html for
+  details.
+
 * particles: initialization of multistep solvers is done with lower
   order methods, so direct convergence tests will fail.
 
-* Code is only known to work with HDF5 1.8.x.
+* code is only known to work with HDF5 1.8.x.
 
-* Code is used mainly with Python 3.5 and later, and it is not tested at
+* code is used mainly with Python 3.5 and later, and it is not tested at
   all with Python 2.x
 
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