Build system is too strict on checking for document links

### Describe the bug

When we write documentation we need to refer to HTML files that do not yet exist (e.g., generated schematics) on the deploy site. The generated schematics would likely be part of the add of the same pull request as the referring documentation.

### To Reproduce

Create a new html link in a document to an as yet generated schematic in the gen/ area. It may be generatable, but not yet deployed on the production site.

Then push this to a fork and do a pull request. The pull request lint checks will fail.

### Expected behavior

Warnings on dead links.

### Actual behavior

Failure and job stoppage on 'dead' or really 'not yet alive' links.

### Additional: Dart SDK info

_No response_

### Additional: pubspec.yaml

_No response_

### Additional: Context

_No response_