correct documentation about `cmake --build` with targets

via the ``CMAKE_MAKE_PROGRAM`` variable.

When calling the build program, you can also select which "target" is to

be build through appending the name of the target to the build command.

Example: ``cmake --build . all``. The following abstract targets are available:

be build through appending the ``--target`` flag and the name of the target

to the build command.  When using ``make`` as build tool, you can just append

the target name to the command. Example: ``cmake --build . --target all`` or

``make all``.  The following abstract targets are available:

.. list-table::

   :header-rows: 1

   * - ``install``

     - install all target files into folders in ``CMAKE_INSTALL_PREFIX``

   * - ``test``

     - run some simple tests (if configured with ``-D ENABLE_TESTING=on``)

     - run some tests (if configured with ``-D ENABLE_TESTING=on``)

   * - ``clean``

     - remove all generated files