docs(mappers): time no longer dates detection

Eight mappers (Cortex XDR, CrowdStrike, Rapid7) still called the OCSF
`time` field "the MTTD anchor" that Riposte reads to stamp detected_at.
Riposte retired MTTD in migration 0256 and stamps detection at
ingestion for every alert; the mappings stay, as the alert's own record
of when the source saw the event. Comments only: no mapping changes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

integrations/rapid7-insightidr/mappers/get_investigations_full.yaml

@@ -67,7 +67,9 @@ ocsf:
   - { source_path: "organization_id",    ocsf_field: "cloud.org.uid" }
   - { source_path: "assignee.name",      ocsf_field: "assignee.name" }
   - { source_path: "assignee.email",     ocsf_field: "assignee.email_addr" }
-  # ── Detection time: the MTTD anchor ───────────────────────────────
+  # ── Event time (OCSF `time`) ───────────────────────────────────────
+  # Riposte no longer reads it to date detection (MTTD retired, migration 0256):
+  # it is the alert's own record of when the source saw the event.
   # Weakest first, strongest last. The investigation is created after the alert that
   # opened it; the alert's own alerted_at is when the event happened in the source system.
   - { source_path: "created_time",       ocsf_field: "time" }