Unify DMARC pass/fail chart naming on "DMARC compliance" (#865)

* Unify DMARC pass/fail chart naming on "DMARC compliance"

The same metric had three names across the dashboards: the pass/fail
pie chart was "Passed DMARC" (OpenSearch, Splunk) and "DMARC Passage"
(Grafana), while the per-domain table column added in #834 was
"% DMARC Compliant". Converge on the compliance wording, which already
anchored the "Message volume and DMARC compliance by from domain"
panels in every dashboard family:

- Pie chart: "DMARC compliance" ("DMARC Compliance" in Grafana, which
  title-cases panel names; OpenSearch and Splunk use sentence case).
- Line chart: "DMARC passage over time" -> "DMARC compliance over
  time" everywhere, so the pie rename doesn't leave the same
  inconsistency one panel down.
- Splunk filter dropdown label: "Passed DMARC" -> "DMARC compliant".
- Grafana Guide panel text and docs/source/kibana.md prose updated to
  match, plus a pre-existing typo fix ("pie charts. you").

Field names, tokens, and queries (passed_dmarc / dmarc_passed) are
untouched; only human-facing titles, labels, and prose changed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Fix "pie charts. you" typo in the Grafana Guide panel text

The period-for-comma typo fixed in docs/source/kibana.md also existed
in the Grafana Guide panel markdown, in both duplicated copies of the
guide text (content and options.content). Caught by Copilot review on
PR #865.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Sync the Grafana Guide panel walkthrough with the current panels

The Guide text described a three-column table layout with a from-domain
list "on the right" and directed readers to a "Message From Header"
table, but the dashboard has two table columns (Reporting Organisations
on the left; Top 2000 Message Sources by Reverse DNS on the right with
Message volume and DMARC compliance by from domain below it) and no
Message From Header table. Point the walkthrough at the real panel
titles and mention the per-domain compliance percentage the table
shows, mirroring the kibana.md walkthrough updated in #834. Both
duplicated copies of the guide markdown (content and options.content)
remain identical.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Scope the CHANGELOG rename claim to dashboards that have the charts

The bullet said the pass/fail charts were renamed "across the ...
Grafana dashboards", but the PostgreSQL Grafana variant has no
pass/fail pie or over-time chart, so the claim quantified over a
dashboard it doesn't apply to. Name the affected dashboards explicitly
and note the PostgreSQL variant is unchanged. Caught by Copilot review
on PR #865.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

docs/source/kibana.md

@@ -38,7 +38,7 @@ valid when a message is forwarded without changing the from address, which is
 often caused by a mailbox forwarding rule. This is because DKIM signatures are
 part of the message headers, whereas SPF relies on SMTP session headers.
 
-Underneath the pie charts. you can see graphs of DMARC passage and message
+Underneath the pie charts, you can see graphs of DMARC compliance and message
 disposition over time.
 
 Under the graphs you will find the most useful data tables on the dashboard. On