Testing external links

[jamesreprise]

Problem to Solve

We have infrastructure for testing our internal links are correct, but not external links. This has given rise to errors:
#610
#611

Current Workaround

Spot them manually and fix them.

Proposed Solution

Check status codes of links at the very least to determine if the link is active. This might be too shallow but is a good 80/20 solution.

Additional Information

This is a thorny problem - we want to check that many external links are valid quickly. CI running this job in particular might be difficult: from an outside perspective, if some cloud IP starts hitting your site very quickly you might be inclined to ratelimit or block it entirely.

[izmalk]

Shall we move this to the https://github.com/vaticle/web-docs ?

[alexjpwalker]

Shall we move this to the https://github.com/vaticle/web-docs ?

test-links is a CI job run on every git push to this repo, docs. We would most likely resolve this issue by updating test-links. So docs is the right place for it.