Add my Dev Container Template to index

Author: m-umair-khan-dev

_data/collection-index.yml

@@ -992,3 +992,8 @@
   contact: https://github.com/RouL/devcontainer-features/issues
   repository: https://github.com/RouL/devcontainer-features
   ociReference: ghcr.io/roul/devcontainer-features
+- name: TTCN-3-Devcontainer
+  maintainer: Muhammad Umair Khan
+  contact: https://github.com/m-umair-khan-dev/devcontainers/issues
+  repository: https://github.com/m-umair-khan-dev/devcontainers
+  ociReference: ghcr.io/m-umair-khan-dev/devcontainers/ttcn-3-devcontainer