Add devcontainer feature for Astronomer (devcontainers#126)

Author: fhoda

_data/collection-index.yml

@@ -218,3 +218,8 @@
   contact: https://github.com/mamba-org/devcontainer-features/issues
   repository: https://github.com/mamba-org/devcontainer-features
   ociReference: ghcr.io/mamba-org/devcontainer-features
+- name: Astronomer Features
+  maintainer: fhoda
+  contact: https://github.com/astronomer/devcontainer-features/issues
+  repository: https://github.com/astronomer/devcontainer-features
+  ociReference: ghcr.io/astronomer/devcontainer-features