[v3 checks] Astro.cookies existing examples

[sarah11918]

📚 Subject area/topic

Astro.cookies

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

https://docs.astro.build/en/guides/server-side-rendering/#astrocookies ( line 227)
https://docs.astro.build/en/reference/api-reference/#astrocookies (line 206)
https://docs.astro.build/en/guides/backend/google-firebase/#creating-pages (lines 357, 434, 476)

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

Need @matthewp to check these code examples and see whether anything needs updating for v3.0 in light of PR 7888 - Astro.cookies.get(key) will return undefined if the cookie does not exist.

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

no reproduction

[matthewp]

One PR: #4302

[matthewp]

That should be the only thing, the API docs are updated in next.

[sarah11918]

Closed as completed! Thank you Matthew!