* [DOCS] Adds a section on runtime fields to the Discover intro * [DOCS] Updates images * Adds link to runtime fields doc * [DOCS] Adds note about filtering, editing, and deleting runtime fields Co-authored-by: KOTungseth <kaarina.tungseth@elastic.co> Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>