added note about marker comments for auto-generating C++ files.

git-svn-id: svn://bind10.isc.org/svn/bind10/branches/jinmei-dnsrdata2@969 e5f2f494-b856-4b98-b285-d166d9295462

src/lib/dns/cpp/rdata/template.h

@@ -37,10 +37,15 @@
 // "RR-type specific members" space (please make them private).  In addition,
 // you may want to define some specific member functions, either public or
 // private (or, though unlikely for a leaf class, protected).
+//
+// Note: do not remove the comment lines beginning with "BEGIN_" and "END_".
+// These are markers used by a script for auto-generating build-able source
+// files.
 
 class MyType : public Rdata {
 public:
     // BEGIN_COMMON_MEMBERS
+    // Do not remove the BEGIN_xxx and END_xxx comment lines.
     // END_COMMON_MEMBERS
 private:
     // RR-type specific members are here.