Misleading file path given in traffic light docs

[m-kro]

The doc says that the "file" attribute works the same as with normal detectors, but in fact actuated traffic lights do not know the magic value NULL for file paths to discard the output. Instead a file with this name is created and written to.

[m-kro]

Actually the detector docs use NUL, but the TL page gives an example with NULL.