Check roxygen code example as well with deps-in-desc hook

[lorenzwalthert]

Is your feature request related to a problem? Please describe.

Would complement parsable-roxygen hook, since roxygenizing won't work if there are dependencies in examples that are not declared in DESCRIPTION while parsable-roxygen passes.

Describe the solution you'd like

Check examples in roxygen comments for missing dependencies.

Describe alternatives you've considered

Accept that parsable-roxygen is not all you need to ensure roxygenise hook will work or just use roxygenise hook.