Hacker Card Jam: warn users about wire length impedance

We recently got an awesome board to OnBoard built with the Hacker Card jam, but the board doesn't work because the wires are too long to be powered over NFC. We should warn users about that when making their own boards.

https://github.com/hackclub/OnBoard/tree/main/projects/thomasNFCArt

Start by reviewing the issue description and the linked project at projects/thomasNFCArt to identify where guidance for making boards is presented. Add a warning about wire length and NFC power limitations, and verify that users see it before making their own boards.

Written by the indexing model from the issue text.