Add Cozystack Maintainers

[kvaps]

As part of cncf/sandbox#351

Pre-submission checklist

If you're adding a new maintainer to the CSV file, please review each of these actions as well:

• The maintainer has updated their LFX Individual Dashboard profile.
• You've sent an email with the addresses to [email protected] for access to Service Desk and mailing lists.
• Optional: You've also sent a PR with updates to cncf/gitdm.

[krook]

@kvaps, @gecube and @tym83 have been added to the CNCF maintainer list and Service Desk (Jira). You'll be added to the mailing list for CozyStack once it's created.