Add kvokka devcontainers repo (#539)

Author: kvokka

_data/collection-index.yml

@@ -298,6 +298,11 @@
   contact: https://github.com/swift-server-community/swift-devcontainer-features/issues
   repository: https://github.com/swift-server-community/swift-devcontainer-features
   ociReference: ghcr.io/swift-server-community/swift-devcontainer-features
+- name: Kvokka Dev Container Features
+  maintainer: kvokka
+  contact: https://github.com/kvokka/features/issues
+  repository: https://github.com/kvokka/features
+  ociReference: ghcr.io/kvokka/features
 - name: gickis Dev Container Features
   maintainer: Andrii Tararaka
   contact: https://github.com/gickis/devcontainer-features/issues