`pattern` option is not passed in `engineOptions`

[willeastcott]

Check out the docs:

https://github.com/metalsmith/layouts#pattern

It says that pattern is a property of engineOptions:

metalsmith(__dirname).use(
  layouts({
    engineOptions: {
      pattern: '**/*.html'
    }
  })
)

However, the code does:

https://github.com/metalsmith/layouts/blob/43394b23f81b210cdfb38b14dbbba4d83bd7361d/src/index.js#L121

This suggests the docs example should be:

metalsmith(__dirname).use(
  layouts({
    pattern: '**/*.html'
  })
)