`includes file=<path>` immediately violates `missing-cmd-help` lint check

[muzimuzhi]

When a usage spec uses includes file=<path>, usage lint always shown a missing-cmd-help info, even when the included usage spec is empty.

$ echo 'include file="./myscript_overrides.usage.kdl"' > myscript.usage.kdl
$ echo "" > myscript_overrides.usage.kdl
$ usage lint myscript.usage.kdl
[INFO  usage::spec] include: ./myscript_overrides.usage.kdl
info [missing-cmd-help] at cmd myscript_overrides.usage.kdl: Command has no help text

Found 0 error(s), 0 warning(s), 1 info(s)

$ usage --version
usage-cli 5.0.0