Release note: add duk_copy()

RELEASES.txt

@@ -333,6 +333,8 @@ Planned
   duk_compile_lstring()) and avoid interning the source code when compiling
   from a user provided string (useful in low memory environments)
 
+* Add duk_copy() API call, essentially shorthand for duk_dup() + duk_replace()
+
 * Align duk_to_fixed_buffer() arguments and return value with duk_to_buffer()
   (this is an API incompatible change); add duk_to_dynamic_buffer()