regen
Libdoc: Correct if for js disabled box. Affected only styles.
UG: Enhancements to Libdoc section.

- Higher level section (visible in the local toc) for internal linking.
- New section about how Libdoc represents arguments.
- Recommend to use new code style (#1802) wheren referring to arguments.
  This includes explicitly recommending not to use single backtics for
  that to avoid accidentally creating links.