[v11.1.x] alerting: notes on label matchers (#89326)

alerting: notes on label matchers (#89269)

* alerting: notes on label matchers

* routing clarification

* Update docs/sources/alerting/alerting-rules/templating-labels-annotations.md

Co-authored-by: brendamuir <100768211+brendamuir@users.noreply.github.com>

* Update docs/sources/alerting/fundamentals/notifications/templates.md

Co-authored-by: brendamuir <100768211+brendamuir@users.noreply.github.com>

---------

Co-authored-by: brendamuir <100768211+brendamuir@users.noreply.github.com>
(cherry picked from commit 0cc67bb93d)

Co-authored-by: antonio <45235678+tonypowa@users.noreply.github.com>

docs/sources/shared/alerts/how_label_matching_works.md

@@ -25,7 +25,9 @@ A label matchers consists of 3 distinct parts, the **label**, the **value** and
   | `=~`     | Select labels that regex-match the value.          |
   | `!~`     | Select labels that do not regex-match the value.   |
 
+{{% admonition type="note" %}}
 If you are using multiple label matchers, they are combined using the AND logical operator. This means that all matchers must match in order to link a rule to a policy.
+{{% /admonition %}}
 
 **Label matching example**