Add eriknw as contributor (#7343)

doc/developer/about_us.rst

@@ -152,6 +152,7 @@ to add your name to the bottom of the list.
 - Flavio Furia, Github: `https://github.com/flaviofuria`
 - Sebastiano Vigna, Github: `https://github.com/vigna`
 - Aaron Zolnai-Lucas, GitHub: `aaronzo <https://github.com/aaronzo>`_, LinkedIn: `aaronzolnailucas <https://www.linkedin.com/in/aaronzolnailucas/>`_
+- Erik Welch, GitHub: `eriknw <https://github.com/eriknw>`_, LinkedIn: `eriknwelch <https://www.linkedin.com/in/eriknwelch/>`_
 
 A supplementary (but still incomplete) list of contributors is given by the
 list of names that have commits in ``networkx``'s