Ship the Stylelint Polaris docs to polaris.shopify.com

[sam-b-rose]

We need a place on the Polaris site to document Polaris tooling. Let's start by adding the Stylelint Polaris documentation to the site in a new section. We can follow up by moving the rest of the Polaris repo Github docs, like Tophatting, onto the site as well.

The rule documentation currently in Shopify/polaris/stylelint/README.md should move to Shopify/polaris/stylelint/polaris.shopify.com/pages. The rule guidance should be concise and actionable, but still enough information to convey why and how to avoid the error in the future.

See these linting rule docs for examples:

• ES Lint example
• Rust example