Merge #14966: docs: fix testmempoolaccept CLI syntax

b74a52192b fix testmempoolaccept CLI syntax (1Il1)

Pull request description:

  `testmempoolaccept "hexstring"` will give a "JSON parse error". The correct syntax is `testmempoolaccept \[\"hexstring\"\]` (but seems escaping is not displayed in other areas so leaving backspaces out).

Tree-SHA512: ad755147d6db0bd3f2d8481517dab29df755a32b28a3bdb4553b1fddd1940850450d1e9a6c3bd04e4e3faa7bc09aadfd3412b4cd65e61d61ea34452831597967

src/rpc/rawtransaction.cpp

@@ -1135,7 +1135,7 @@ static UniValue testmempoolaccept(const JSONRPCRequest& request)
             "Sign the transaction, and get back the hex\n"
             + HelpExampleCli("signrawtransactionwithwallet", "\"myhex\"") +
             "\nTest acceptance of the transaction (signed hex)\n"
-            + HelpExampleCli("testmempoolaccept", "\"signedhex\"") +
+            + HelpExampleCli("testmempoolaccept", "[\"signedhex\"]") +
             "\nAs a JSON-RPC call\n"
             + HelpExampleRpc("testmempoolaccept", "[\"signedhex\"]")
             );