Update docs/processing-payments-with-stripe (#22431)
Update docs/processing-payments-with-stripe (#22431)

* Update docs/processing-payments-with-stripe

* Link to ecommerce example code

* Edit Stripe guide changes for clarity

Co-authored-by: Aisha Blake <0361fe97c7c02ef86800dedecb1220f5cf5f3320@gatsbyjs.com>
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