docs: Update resolvers.md

[wlukorito]

Summary

Docs for @feathersjs/schema show imports for schemaHooks but there's no such export. The package exports hooks instead. Following the docs would give the below error:

"@feathersjs/schema" has no exported member 'schemaHooks

Use named export hooks and alias it as schemaHooks

[daffl]

Good catch, thank you!