While not required, some contestants in previous seasons have added a
short comment at the end of their entry explaining that it had been
written for the competition. They included links to the community, the
topic, and anything else they thought might be useful.
Others put this information at the beginning of the entry and some left
it off completely. If you choose to include it, you may want to be sure
that it is somehow distinguishable from the rest of the entry. A simple way to do that is with a font change:
< font size=-2>This is some explanatory text, but isn’t really part of the entry</font>