Attempt to protect copy-paste-happy programmers from themselves.

Judging by issue 469, "copy-paste whatever piece of code I come across
without even reading it and then whine" is a popular programming
technique. Since I cannot change significantly this behavior, I'm
replacing the configuration example with something harmless but slightly
obnoxious and adding a warning that will only ever be read by people who
don't need it, in an attempt to dam the flow of complaints.