Add New Maintainer

[martialblog]

Hey,

first of: great project.

However, given there there are no more updates recently, I'd suggest adding a new maintainer. So that there aren't endless forks and we can ensure new features.

Of course, I'd volunteer myself if you don't mind. It's been a while since I contributed ( https://github.com/timdaman/check_docker/pull/58 ), but I know my way around the code.

Cheers, Markus