Maintainer Cleanup

[majormoses]

Right now there is tribal knowledge on how maintainers are selected and this was highlighted in #123 (comment). Additionally when reviewing the list of maintainers there are some old maintainers who we should probably remove or limit their access as they are no longer involved in the project.

We should create something based on but suited to our needs from https://github.com/sensu-plugins/community/blob/master/HOW_TO_BECOME_A_MAINTAINER.md.

• Create a Maintainers Doc or a section in the readme

• Discuss if we should remove or downgrade access of non active maintainers

• Follow up on non active maintainers