chore(upload-client): update readme

Author: nd0ut

Diff for: packages/upload-client/README.md

@@ -457,7 +457,11 @@ Or `Blob` like this:
 ```ts
 const uri = 'URI_TO_FILE'
 const blob = await fetch(uri).then((res) => res.blob())
-uploadFile(blob, { publicKey: 'YOUR_PUBLIC_KEY' })
+uploadFile(blob, {
+  publicKey: 'YOUR_PUBLIC_KEY',
+  fileName: 'file.txt',
+  contentType: 'text/plain'
+})
 ```
 
 ## Testing