It's actually impossible to miss!
The whole Donkey Kong program is just hexadecimal codes, each of which translate to Z80 commands, except for those lines. When you look at the program as ASCII text, the message is there.
If anybody wants to see it, you can go into dkong.zip and look. It's in the c_5at_g.bin file. Extract (copy/paste) that file from the zip, change the extension to .txt and open it in your browser or whatever. (Or leave it as .bin and try hexecute
if you want it to look tidier).
Scroll to the bottom and you will see it. The first few words are cut off in the US version, though (I guess they needed the space for the changes they made to the program).
If you want to see the whole thing, it's in c_5k_b.bin of the Japan ROMset.