Migrate blog and docs starters to content collections

[bholmesdev]

Changes

• Migrate blog and docs to content collections
• Remove with-content example

Testing

If it smokes, we're good!

Docs

README updates on blog starter

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Latest commit: a8a1050

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[sarah11918]

Looks good to Docs, Ben! 💪

I'd punch up that one sentence, but otherwise, no need for this to collect dust in pulls. 🚀

[natemoo-re]

This looks good overall, but I'd love to see one more pass for code consistency.

For example:

• Some places reference import * as CONSTS from '../consts' but then only reference one named export, some places reference import { SITE } from '../consts'.
• There are lots of as Props littered throughout the code, would be nice to clean this up while we're doing a refactor.