Showcase grown team of maintainers in the GitHub organisation

[almereyda]

While the Planka project itself has a nice list of contributors

the GitHub organisation does not. It is a voluntary setting by people that are added to

• https://github.com/orgs/plankanban/people

to also choose to display their membership in the organisation there.

Given the recent surge of activity and stabilisation of team and processes, it could be nice to see some more of the involved maintainers, if they like to. This way visitors and strangers who come by would find that it is actually a group effort and not standing on the shoulders of a single person alone.