Ensure private API is not enumerable

[natemoo-re]

Changes

• Previously, we created a privateRenderMarkdownDoNotUse on the Astro global.
• This property was enumerable and showed up when users did console.log(Astro).
• This PR makes this value non-enumerable and also makes the name __renderMarkdown.

Testing

Hoping CI doesn't break 🤞🏻

Docs

Internal change only

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🦋 Changeset detected

Latest commit: 25f2f2d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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astro	Patch

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[bholmesdev]

For something mark "do not use," we sure made it easy to use huh?

[matthewp]

It could also be a Symbol() and would be about as private as you can get (you could only get to it through Object.getOwnPropertySymbols). Or you could use a WeakMap to make it actually private. I don't particularly care, just throwing out options.

[natemoo-re]

Welp, I merged this as you were leaving that comment. Either would be fine, but I'm not too concerned about it actually being private. Just removing it from console.log(Astro) should be fine.