Add Krkn slack channel

This commit adds a slack channel for Krkn project - https://github.com/redhat-chaos/krkn,
a chaos testing tool for Kubernetes focusing on resilience and performance validation
under failure conditions.

This channel will act a discussion place for the Kubernetes community interested
in the Krkn tooling and methodology as well Chaos and Performance Engineering.

Author: chaitanyaenr

communication/slack-config/channels.yaml

@@ -537,3 +537,4 @@ channels:
   - name: yaml-overlay-tool
   - name: zarf
   - name: zarf-dev
+  - name: krkn