[docs][guides] New Reference Guide on working with Stripe

[AishaBlake]

Summary

As part of the ongoing effort to improve on the top 25 learning workflows identified in #13708, we'd like to add a Reference Guide on working with Stripe in Gatsby. This will be one of several guides added as part of the e-commerce workflow.

Some recommended topics to cover:

• setting up your Stripe account
• Stripe Elements vs. Stripe Checkout
• existing plugins and starters using Stripe (like gatsby-plugin-stripe)
• recurring payments & auth

Motivation

The ability to build e-commerce sites with Gatsby gives developers (and business owners) a lot of flexibility. We'd like to provide a starting point for folks using some of the most popular e-commerce tools.

Steps to resolve this issue

Draft the doc

• Write the doc, following the format listed in these resources:
  • Overview on contributing to documentation
  • Docs Templates
  • Example of a guide to imitate
  • Example of a similar article
• Add the article to the docs sidebar under the "Building an E-commerce Site" section.

Open a pull request

• Open a pull request with your work including the words "closes #[this issue's number]" in the pull request description

[connorlindsey]

I just finished a project using gatsby checkout for one-time payments and elements for creating subscriptions with Stripe billing. I’d love to get involved and will start working on this. If anyone else wants to help, let me know.

[AishaBlake]

That sounds great, @connorlindsey! Thanks! Please note that the team will mostly be on vacation through the end of the year, so responses will be delayed.