[DOC] Remove documentation error in graphs.pyx

[acostadon]

Report incorrect or missing documentation

Extra line in docs of graphs.pyx

Provide links and line numbers if applicable. https://github.com/rapidsai/cugraph/blob/branch-22.12/python/pylibcugraph/pylibcugraph/graphs.pyx#L120

Describe the problems or issues found in the documentation Remove the Extra line in docs of graphs.pyx