Add note regarding debugging. (#22)

Author: tobiasraabe

README.rst

@@ -99,6 +99,16 @@ You can also set the options in one of the configuration files (``pytask.ini``,
     parallel_backend = loky  # or processes or threads
 
 
+Warning
+-------
+
+It is not possible to combine parallelization with debugging. That is why ``--pdb`` or
+``--trace`` deactivate parallelization.
+
+If you parallelize the execution of your tasks using two or more workers, do not use
+``breakpoint()`` or ``import pdb; pdb.set_trace()`` since both will cause exceptions.
+
+
 Changes
 -------