Add information about Astro.context

[laptou]

What kind of changes does this PR include?

• New or updated content

Description

Adds information about Astro.context, introduced in withastro/astro#3934

[netlify[bot]]

✅ Deploy Preview for astro-docs-2 ready!

Built without sensitive environment variables

Name	Link
🔨 Latest commit	1a7bc37792cc9266a3341e6dde6e0e15bb099571
🔍 Latest deploy log	https://app.netlify.com/sites/astro-docs-2/deploys/62d0b44e507e6400084e7766
😎 Deploy Preview	https://deploy-preview-1003--astro-docs-2.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.

[delucis]

Thanks for this @laptou! I'm going to mark it as a draft so we don't accidentally merge it before the PR to Astro is discussed.

[sarah11918]

Hi @laptou, I can see that the associated PR to the Astro repo was closed, and an RFC was requested if you want to go through the channels to implement this feature. So, I am also closing this docs PR which can be reopened if the corresponding Astro feature is merged!