documentation

Pull request #2110: DEV-3947 changed the comment for the last(/host/key) function using proper syntax (sub-issue 19)

Merge in WEB/documentation from feature/DEV-3947-6.0-D19 to release/6.0

* commit '4c770a8c67c69c6abbf82b25cc76b29a9b6fa268':
  DEV-3947 missing dot added (sub-issue 19).
  DEV-3947 "date and time" and nodata() functions" changed to "date and time" and/or nodata() functions", link to the calculation time is provided (sub-issue 19.1)
  DEV-3947 term "time-based functions" changed to "date and time" and nodata() functions" (sub-issue 19.1)
  DEV-3947 clarification to avoid confusion between date and time function and time-based functions (sub-issue 19.1)
  DEV-3947 changed the comment for the last(/host/key) function using proper syntax (sub-issue 19)