Adding quotes on Sending proof Command

Step 3: Play a Game and Send Your Proof
Once you have your key and have won a game, you can submit your proof for verification.

Use the send command with the following format:

```
soundness-cli send --proof-file "<proof-blob-id>" --game "<game-name>" --key-name "<your-key-name>" --proving-system "ligetron" --payload '<json-payload>'
```