master13225
* updates to new features for synthetics * adding javascript and collapse content * adding callout and moving advanced options * adding some collapse sections, * updating variables shortcode * PM feedback * Apply suggestions from code review Co-authored-by: cecilia saixue watt <cecilia.watt@datadoghq.com> * updates from editorial review --------- Co-authored-by: cecilia saixue watt <cecilia.watt@datadoghq.com>