Add clearer instructions to experimental content intellisense setup

[JusticeMatthew]

📚 Subject area/topic

content layer

📋 Suggested page

https://docs.astro.build/en/reference/configuration-reference/#experimentalcontentintellisense

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

Provide clearer instructions for accessing and enabling the setting in VS Code

🖥️ Reproduction of code samples in StackBlitz

No response

[sarah11918]

Hey @JusticeMatthew - often with experimental features... you're on your own! 😅 This is a very new, and early feature. It's not yet ready for prime time, and it's at the stage where it's really just meant to be played with at your own risk to see how the feature will develop.

So we're not going to document more about using it right now, BUT, if you'd like to hunt down the original Astro implementation PR and update the reference entry with a link to it, so people can check out the code, see the initial discussion/thoughts behind the feature, I think that would be a great addition here! Something like:

See the [content Intellisense implementation PR](PR link) for more details about this early feature.

(Also noting that this change must be made in the Astro repo, not the docs repo directly, as source material that gets pulled in.)