remove extra space with unittest cmd

docs/Readme-Python.txt

@@ -519,8 +519,8 @@ Run test in single file
 > python - m unittest - v tests/test_roscop.py
 
 Run all test_ * in dir tests:
-> python - m unittest  discover tests - v
-> python - m unittest  discover - s tests - p 'test_*.py' - v
+> python -m unittest  discover tests -v
+> python -m unittest  discover -s tests -p 'test_*.py' -v
 
 Methods name:
 assertEqual()