rpc: Fix getblocktemplate CLI example (#16594)

src/rpc/mining.cpp

@@ -352,7 +352,7 @@ static UniValue getblocktemplate(const JSONRPCRequest& request)
             "}\n"
                 },
                 RPCExamples{
-                    HelpExampleCli("getblocktemplate", "{\"rules\": [\"segwit\"]}")
+                    HelpExampleCli("getblocktemplate", "'{\"rules\": [\"segwit\"]}'")
             + HelpExampleRpc("getblocktemplate", "{\"rules\": [\"segwit\"]}")
                 },
             }.Check(request);