add feature schema (#33)

Author: jarrodcolburn

.devcontainer.json

@@ -2,6 +2,16 @@
     "image": "mcr.microsoft.com/devcontainers/javascript-node:0-18",
     "customizations": {
         "vscode": {
+            "settings": {
+                "json.schemas": [
+                    {
+                        "fileMatch": [
+                            "*/devcontainer-feature.json"
+                        ],
+                        "url": "https://raw.githubusercontent.com/devcontainers/spec/main/schemas/devContainerFeature.schema.json"
+                    }
+                ]
+            },
             "extensions": [
                 "mads-hartmann.bash-ide-vscode"
             ]
@@ -12,4 +22,4 @@
     },
     "remoteUser": "node",
     "postCreateCommand": "npm install -g @devcontainers/cli"
-}
+}