docs: fix copy-pasta breaking typo in getRecentBlockhash example (#16962)

(cherry picked from commit 3d98321b38)

Co-authored-by: Trent Nelson <trent@solana.com>

docs/src/developing/clients/jsonrpc-api.md

@@ -2161,7 +2161,7 @@ An RpcResponse containing a JSON object consisting of a string blockhash and Fee
 
 Request:
 ```bash
-curl http://localhost:8899 -X POST -H "Content-Type: application/json" -d 'i
+curl http://localhost:8899 -X POST -H "Content-Type: application/json" -d '
   {"jsonrpc":"2.0","id":1, "method":"getRecentBlockhash"}
 '
 ```