Added Opensource config

Author: hiranya911

.opensource/project.json

@@ -0,0 +1,15 @@
+{
+  "name": "Firebase Admin SDK - .NET",
+  "platforms": [
+      ".NET",
+      "Admin"
+  ],
+  "content": "README.md",
+  "pages": [],
+  "related": [
+      "firebase/firebase-admin-go",
+      "firebase/firebase-admin-java",
+      "firebase/firebase-admin-node",
+      "firebase/firebase-admin-python"
+  ]
+}