cli: improve -netinfo invalid argument error message

src/bitcoin-cli.cpp

@@ -379,7 +379,7 @@ public:
             if (ParseUInt8(args.at(0), &n)) {
                 m_details_level = std::min(n, MAX_DETAIL_LEVEL);
             } else {
-                throw std::runtime_error(strprintf("invalid -netinfo argument: %s", args.at(0)));
+                throw std::runtime_error(strprintf("invalid -netinfo argument: %s\nFor more information, run: bitcoin-cli -netinfo help", args.at(0)));
             }
         }
         UniValue result(UniValue::VARR);