To generate the Tiled documentation, you need to install Python 3, Sphinx and
the ReadTheDocs theme.

On Ubuntu the following commands could be used:

    sudo apt install python3-pip
    pip3 install sphinx
    pip3 install sphinx_rtd_theme

Or, alternatively:

    sudo apt install python3-sphinx-rtd-theme

Then, the documentation can be generated by running:

    make html
