[4027] added some explanatory comments for Pkt4o6::pack().

src/lib/dhcp/pkt4o6.cc

@@ -48,10 +48,14 @@ Pkt4o6::Pkt4o6(const Pkt4Ptr& pkt4, const Pkt6Ptr& pkt6)
 }
 
 void Pkt4o6::pack() {
+    // Convert wire-format Pkt4 data in the form of OptionBuffer.
     Pkt4::pack();
     OutputBuffer& buf = getBuffer();
     const uint8_t* ptr = static_cast<const uint8_t*>(buf.getData());
     OptionBuffer msg(ptr, ptr + buf.getLength());
+
+    // Build the DHCPv4 Message option for the DHCPv6 message, and pack the
+    // entire stuff.
     OptionPtr dhcp4_msg(new Option(Option::V6, D6O_DHCPV4_MSG, msg));
     pkt6_->addOption(dhcp4_msg);
     pkt6_->pack();