Merge bitcoin/bitcoin#29687: cli: improve bitcoin-cli error when not connected

69d6fd6 cli: improve bitcoin-cli error when not connected (willcl-ark)

Pull request description:

  Closes: #29555

  Simply adds an additional suggestion to check `bitcoin-cli -help`.

ACKs for top commit:
  maflcko:
    lgtm ACK 69d6fd6
  itornaza:
    tested ACK 69d6fd6
  tdb3:
    ACK for 69d6fd6

Tree-SHA512: af0c712bcc9b1267f81a8316d015bef99ab788ef43e3b450cdc4a9cb74004727d757d48f50d3af2b28b01be2931578623311677a79f1b148a53f364bd4279a0c

Author: fanquake

src/bitcoin-cli.cpp

@@ -827,7 +827,10 @@ static UniValue CallRPC(BaseRequestHandler* rh, const std::string& strMethod, co
         if (response.error != -1) {
             responseErrorMessage = strprintf(" (error code %d - \"%s\")", response.error, http_errorstring(response.error));
         }
-        throw CConnectionFailed(strprintf("Could not connect to the server %s:%d%s\n\nMake sure the bitcoind server is running and that you are connecting to the correct RPC port.", host, port, responseErrorMessage));
+        throw CConnectionFailed(strprintf("Could not connect to the server %s:%d%s\n\n"
+                    "Make sure the bitcoind server is running and that you are connecting to the correct RPC port.\n"
+                    "Use \"bitcoin-cli -help\" for more info.",
+                    host, port, responseErrorMessage));
     } else if (response.status == HTTP_UNAUTHORIZED) {
         if (failedToGetAuthCookie) {
             throw std::runtime_error(strprintf(