Draft: Relay cape doc numeral one

This is a short on the ideas I have found to be true regarding the RelayCape at relay.rst at https://git.beagleboard.org/silver2row/docs.beagleboard.io/-/blob/5d5fc2ce569ce7abde1bfaa01294a24aa95f6db4/boards/capes/relay.rst .

Seth

P.S. My naming on this site is silver2row. Please do allow me to know what is incorrect to you, please let others know so they can elaborate, and please let me know what you are willing to accept. This way, I can further help you and others in their journey of electronics, am335x related ideas, and for the BBB usages. This is a start!