Koa main page broken

# Documentation bug

## Summary
Koa **main page** doesn't load for me.


the rest of the package seems ok

[guide.md](https://github.com/koajs/koa/blob/master/docs/guide.md) could probably be the main page. It's already scraped.

Start by opening the linked Koa docs/guide.md and comparing it with the current Koa main page. Confirm why the main page fails while the rest of the package loads; done means Koa opens on guide.md without affecting the other Koa pages.

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