docs suggestion: monetizing your app

### Problem

Just suggesting point of clarification, for this source: https://github.com/elementary/docs/blob/master/appcenter/monetizing-your-app.md
(which ends up [here](https://docs.elementary.io/develop/appcenter/monetizing-your-app), correct?)

I was curious what happens if a user wants to pay an amount less than $1 or $0.50, is the platform fee still charged?
Then I checked the Stripe payment for main elementary.io "Pay what you can" and any value < $1 goes straight to Download, rather than attempting to collect payment, so I assume that's how your AppStore works as well.

### Proposal

Add a sentence like "$1 is the minimum payment a user can enter."

Or, possibly re-word the section as:

> For payments $1.69 and above, fee is 30%. For payments between $1 and $1.68, fee is $0.50. Payments below $1 are not currently accepted by Stripe.

(If I'm wrong about the $1 minimum, just clarify what actually happens)

### Prior Art (Optional)

_No response_