Detect broken links?

[lidel]

@hacdias ipfs/specs#385 introduced a 🐛 -- we have some broken links which were not caught by generator:

• https://bafybeibbvzuwv2fs3x5pwjydoiht5zqsolxfuuw55o5uzwt2ne5ojy7noe.ipfs.dweb.link/ipips/ipip-0337/#detailed-design

[hacdias]

Note for future:

• Plugin that detects broken external links: https://www.npmjs.com/package/eleventy-plugin-broken-links