/usr/share/cmake-3.10/Help/envvar/ is in cmake-data 3.10.2-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/cmake-3.10/Help/envvar/ASM_DIALECT.rst
/usr/share/cmake-3.10/Help/envvar/ASM_DIALECTFLAGS.rst
/usr/share/cmake-3.10/Help/envvar/CC.rst
/usr/share/cmake-3.10/Help/envvar/CFLAGS.rst
/usr/share/cmake-3.10/Help/envvar/CMAKE_CONFIG_TYPE.rst
/usr/share/cmake-3.10/Help/envvar/CMAKE_MSVCIDE_RUN_PATH.rst
/usr/share/cmake-3.10/Help/envvar/CMAKE_OSX_ARCHITECTURES.rst
/usr/share/cmake-3.10/Help/envvar/CSFLAGS.rst
/usr/share/cmake-3.10/Help/envvar/CTEST_INTERACTIVE_DEBUG_MODE.rst
/usr/share/cmake-3.10/Help/envvar/CTEST_OUTPUT_ON_FAILURE.rst
/usr/share/cmake-3.10/Help/envvar/CTEST_PARALLEL_LEVEL.rst
/usr/share/cmake-3.10/Help/envvar/CTEST_USE_LAUNCHERS_DEFAULT.rst
/usr/share/cmake-3.10/Help/envvar/CUDACXX.rst
/usr/share/cmake-3.10/Help/envvar/CUDAFLAGS.rst
/usr/share/cmake-3.10/Help/envvar/CUDAHOSTCXX.rst
/usr/share/cmake-3.10/Help/envvar/CXX.rst
/usr/share/cmake-3.10/Help/envvar/CXXFLAGS.rst
/usr/share/cmake-3.10/Help/envvar/DASHBOARD_TEST_FROM_CTEST.rst
/usr/share/cmake-3.10/Help/envvar/FC.rst
/usr/share/cmake-3.10/Help/envvar/FFLAGS.rst
/usr/share/cmake-3.10/Help/envvar/LDFLAGS.rst
/usr/share/cmake-3.10/Help/envvar/MACOSX_DEPLOYMENT_TARGET.rst
/usr/share/cmake-3.10/Help/envvar/RC.rst
/usr/share/cmake-3.10/Help/envvar/RCFLAGS.rst