Cleanup docstrings (flake8 H401, H402, H403, H404)

- docstring should not start with a space (flake8 H401)
- one line docstring needs punctuation (flake8 H402)
- multi line docstring end on new line (flake8 H403)
- multi line docstring should start with a summary (flake8 H404)

Change-Id: I69b414395930bda739aa01b785ac619fa8bb7d9b