The Mint / Grant / Burn function allows you to mint a PKP and atomically assign it to a set of Lit Actions. When you use M/G/B, a signature will only be returned when the logic you've declared in your Lit Action returns 'true'.
Suppose you have a Lit Action that will check if a number is prime, and if it is, sign that number. If it is not prime, the Lit Action will abort. If you were able to mint a PKP, assign it to that Lit Action, and then burn the PKP in a single atomic transaction, then it would be provable that the PKP was not used to sign anything before it was approved to use the Lit Action. In this case, you could trust that any numbers signed with that PKP are indeed prime, without needing to check them yourself. This creates a powerful way to prove the output of any JS code by checking that 1) the signature is valid, 2) the lit action code is correct, and 3) that the PKP was minted using this Mint/Grant/Burn pattern.
Create an example for the developer docs that demonstrates how this functionality can be used.