[v3 checks] Update instances of class:list

[sarah11918]

📚 Subject area/topic

1. class:list directive AND 2. scoped style hashes are lowercase!

📋 Page(s) affected (or suggested, for new content)

https://docs.astro.build/en/reference/directives-reference/#classlist
https://docs.astro.build/en/core-concepts/astro-components/#the-component-template
https://docs.astro.build/en/guides/styling/

📋 General description or bullet points (if proposing new content)

@natemoo-re needs to check docs for any examples that are now counter to the class:list changes for v3.0:

• https://deploy-preview-4166--astro-docs-2.netlify.app/en/guides/upgrade-to/v3/#removed-classlist-features
• https://deploy-preview-4166--astro-docs-2.netlify.app/en/guides/upgrade-to/v3/#removed-passing-classlist-as-a-prop

Including updating some uppercase scoped style hashes e.g. class="astro-KOI4QYR5"

The above listed should be the only three pages that are possibly affected.

🖥️ Reproduction in StackBlitz (if reporting incorrect content or code samples)

none

[sarah11918]

Not sure why this wasn't closed automatically, but closed by #4322 🥳