Use imperative mood in constructor docstring.
Resolves D401 in pydocstyle 5.0.0 and flake8.
Connects to https://github.com/ros2/build_cop/issues/255
Resolves D401 in pydocstyle 5.0.0 and flake8.
Connects to https://github.com/ros2/build_cop/issues/255