[Detections Response][Adhoc Rules] - Document adhoc rule runs feature

[yctercero]

Description

Placeholder docs ticket for upcoming adhoc rule runs feature.

Background & resources

• PRs: TBD
• Issues/metas:
  • https://github.com/elastic/kibana/pull/157144
  • https://github.com/elastic/security-team/issues/2840
  • Manual rule runs - https://github.com/elastic/security-team/issues/2840
  • Provide rule runs gap information https://github.com/elastic/security-team/issues/8558
  • Manual gap fill runs for detection rules https://github.com/elastic/security-team/issues/8559 (depending on timing could be combined with 2840)
  • Automatic backfills of rule execution gaps https://github.com/elastic/security-team/issues/6097
  • Manual rule runs improvements - rule actions and alert suppression settings https://github.com/elastic/security-team/issues/8560 - maybe future
• Point of contact: @yctercero @approksiu
• Test environments: TBD

Which documentation set does this change impact?

ESS and serverless

ESS release

TBD - possibly 8.14

Serverless release

TBD

Feature differences

N/A

API docs impact

TBD

Prerequisites, privileges, feature flags

TBD

[nastasha-solomon]

Copy review being tracked at https://github.com/elastic/security-docs/issues/4650