Wrong typeset of filter in plugin help viewer

[M. Gronle]

When clicking a filter / algorithm, a dataIO or actuator instance in the itom help viewer, the example string is wrongly typeset.
Here an example for dataIO (however it is the same for filters and actuators):

This string is also wrongly copied to the clipboard. The correct typeset contains a space after the first comma:

‌

dataIO("SerialIO", port, baud, endline)

The wrong typeset leads to a warning of the flake8 style checker.

[M. Gronle]

fixes issue #135: correct typeset of example strings in helpTreeDockWidget.cpp

→ <<cset ad4293a481a1>>