Add Hello Plugin with settings pane and metadata

index.json

@@ -0,0 +1,17 @@
+[
+  {
+    "id": "org.devism.hello-plugin",
+    "name": "Hello Plugin",
+    "description": "A greeting demo plugin for ohn — shows how to contribute a settings pane.",
+    "versions": [
+      {
+        "version": "0.1.0",
+        "dependency_name": "ohn-plugin-hello",
+        "api_versions": {
+          "OhnUiPlugin": "1.0"
+        },
+        "download_url": "https://github.com/stoorps/ohn-plugins/archive/refs/heads/main.tar.gz"
+      }
+    ]
+  }
+]