Clarify that the hoomd-contributors team is for Glotzer Group members
Clarify that the hoomd-contributors team is for Glotzer Group members

github does not allow team members from outside an organization.
[ci skip]

joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue