docs: fix s3 presign typo (#16604)

docs/api/s3.md

@@ -175,7 +175,7 @@ To facilitate this, you can presign URLs for S3 files. This generates a URL with
 import { s3 } from "bun";
 
 // Generate a presigned URL that expires in 24 hours (default)
-const url = s3.presign("my-file.txt", {
+const url = s3.file("my-file.txt").presign({
   expiresIn: 3600, // 1 hour
 });
 ```