Fix missing-function-docstring

src/mailcow/menu.py:12:0: C0116: Missing function or method docstring (missing-function-docstring)
src/mailcow/menu.py:51:0: C0116: Missing function or method docstring (missing-function-docstring)
src/mailcow/menu.py:96:0: C0116: Missing function or method docstring (missing-function-docstring)
src/mailcow/config.py:11:0: C0116: Missing function or method docstring (missing-function-docstring)
src/mailcow/config.py:15:0: C0116: Missing function or method docstring (missing-function-docstring)
src/mailcow/config.py:23:0: C0116: Missing function or method docstring (missing-function-docstring)
src/mailcow/config.py:35:0: C0116: Missing function or method docstring (missing-function-docstring)
src/mailcow/config.py:43:0: C0116: Missing function or method docstring (missing-function-docstring)
src/mailcow/utils.py:175:0: C0116: Missing function or method docstring (missing-function-docstring)
src/mailcow/cli.py:20:0: C0116: Missing function or method docstring (missing-function-docstring)