Update README.md

Author: alexleventer

README.md

@@ -4,7 +4,10 @@
 
 ```typescript
 import { AstraDB } from "@datastax/astra-db-ts";
+
+const { TOKEN, DATABASE_ID, REGION, COLLECTION_NAME } = process.env;
+
 const astraDb = new AstraDB(TOKEN, DATABASE_ID, REGION);
-const collection = await astraDb.collection("events");
+const collection = await astraDb.collection(COLLECTION_NAME);
 const results = await collection.countDocuments();
-```
+```