fix(docs): _.merge doesn't concat arrays (#314)
fix(docs): _.merge doesn't concat arrays (#314)

- it's a deep merge that merges them by index
- the rest of the docs are accurate, just this one mention was incorrect

- eventually should move to shallow merge/replace arrays to better
  reflect how `tsconfig` `extends` works, but just fix the docs for now
ezolenko/rollup-plugin-typescript2,ezolenko/rollup-plugin-typescript2