Log group for docs linter doesn't capture all output

[medubelko]

Situation

We have a log group for the docs-lint target, but when it gets around to calling docs-install, the log prints the full output of that target.

Example: https://github.com/canonical/snapcraft/actions/runs/26916691030/job/79407942039?pr=6276#step:6:29

Request

Either:

• Change the group to include dependent target calls. Is that possible? The docs are sparse.
• Give docs-install its own group.