Add New Podlet Discord Channels to the List of Communications Channels

[TheRealBecks]

In the last Podman community meeting (2026-02-03) I already suggested to create Discord channels for the Podlet project, so the developers and the community can use the same collaboration tools as the Podman and Podman-Desktop teams do.

We would like to get these two Discord channels:

• podlet
• podlet-dev

I created containers/podman#28046 for the creation of the channels.

Afterwards we need to alter our documentation.

[k9withabone]

containers/podman#28046 has been completed, and the channels have been created. Now to add them to the communication section in CONTRIBUTING.md.