`B950` ignores `max-doc-length` flake8 configuration option

flake8 has a configuration option max-doc-length, which configures the maximum line length for docstrings. flake8-bugbear currently ignores this setting. It makes sense to limit line length of code to ~80-88 for smaller screen sizes, diffs etc. Especially within tests though, limiting docstring line length to the same value can cause very awkward docstring formatting, severely limiting readability.