fix links, use common link checker

[zeitlinger]

No description provided.

[zeitlinger]

@trask fyi

[codeboten]

Is this shared commonly somewhere? i believe i used the specification as the guiding repo when i updated to lychee last time

[zeitlinger]

Is this shared commonly somewhere?

yes, @trask and I worked on the approach and it's in some of the java repos now - e.g. open-telemetry/opentelemetry-java-instrumentation#14227

This is the first non-java repo I'm targeting.

The advantages of the approach:

1. only check files that have changed to reduce flakiness (if config changed, check all files)
2. can run the check locally as well using mise.jdx.dev/
3. update lychee to enable fragment checking