net: advertise NODE_P2P_V2 if CLI arg -v2transport is on

Co-authored-by: Dhruv Mehta <856960+dhruv@users.noreply.github.com>

src/protocol.cpp

@@ -199,6 +199,7 @@ static std::string serviceFlagToStr(size_t bit)
     case NODE_WITNESS:         return "WITNESS";
     case NODE_COMPACT_FILTERS: return "COMPACT_FILTERS";
     case NODE_NETWORK_LIMITED: return "NETWORK_LIMITED";
+    case NODE_P2P_V2:          return "P2P_V2";
     // Not using default, so we get warned when a case is missing
     }