Utilities/Release: Generate docs on dash2win64 cygwin

Configure the build on dash2win64 cygwin to run Sphinx and generate our
documentation.

Utilities/Release/dash2win64_cygwin.cmake

@@ -10,6 +10,8 @@ set(INITIAL_CACHE "CMAKE_BUILD_TYPE:STRING=Release
 CMAKE_Fortran_COMPILER_FULLPATH:FILEPATH=FALSE
 CTEST_TEST_TIMEOUT:STRING=7200
 DART_TESTING_TIMEOUT:STRING=7200
+SPHINX_HTML:BOOL=ON
+SPHINX_MAN:BOOL=ON
 ")
 set(CXX g++)
 set(CC  gcc)