doc: mark the codeblock as sh

Author: wjmelements

README.md

@@ -205,6 +205,6 @@ forge test --match-path test/ERC721/SafeTransfer.t.sol
 1. Fund the factory creator account, `0x3ef96E9f82CaFE4a05183b59e7671E39B6b26347`, with 0.2 FIL.
 2. Replay the [legacy CREATE transaction](./deploy.json) onto any Filecoin network.
 
-```
+```sh
 curl --header "Content-Type: application/json" --data @deploy.json $RPC_URL
 ```