documentation

Pull request #3249: feature/ZBX-26202-7.0-D. Admin and User type users may now create 'Execute now' tasks; added "Execute now" page (and other) refinements.

Merge in WEB/documentation from feature/ZBX-26202-7.0-D to release/7.0

* commit 'f45221a1e06eb27568188e244797aa64cd4c277e':
  [ZBX-26202] added note explaining meaning of "type": "7" in Task object
  [ZBX-26202] added missing item type (Browser) to the list of item types supporting "Execute now"
  [ZBX-26202] updated task.get method description
  [ZBX-26202] Admin and User type users may now create 'Execute now' tasks
  [ZBX-26202] refined "Execute now" page