chore: add setDevkey and upsertDocument methods

docs/examples/databases/upsert-document.md

@@ -2,12 +2,14 @@ import 'package:appwrite/appwrite.dart';
 
 Client client = Client()
     .setEndpoint('https://<REGION>.cloud.appwrite.io/v1') // Your API Endpoint
-    .setKey(''); // 
+    .setProject('<YOUR_PROJECT_ID>'); // Your project ID
 
 Databases databases = Databases(client);
 
-DocumentList result = await databases.createDocuments(
+Document result = await databases.upsertDocument(
     databaseId: '<DATABASE_ID>',
     collectionId: '<COLLECTION_ID>',
-    documents: [],
+    documentId: '<DOCUMENT_ID>',
+    data: {},
+    permissions: ["read("any")"], // optional
 );