Remove outdated comment about NTP

The comment has been around since 0.1, but NTP inside the client
isn't deemed necessary so remove the comment to avoid confusion.

src/net.cpp

@@ -445,7 +445,6 @@ void CNode::PushVersion()
 {
     int nBestHeight = g_signals.GetHeight().get_value_or(0);
 
-    /// when NTP implemented, change to just nTime = GetAdjustedTime()
     int64_t nTime = (fInbound ? GetAdjustedTime() : GetTime());
     CAddress addrYou = (addr.IsRoutable() && !IsProxy(addr) ? addr : CAddress(CService("0.0.0.0",0)));
     CAddress addrMe = GetLocalAddress(&addr);