add banners settings doc (#94672) (#95006)

* add banners settings doc

* address review comments

* add link to the correct file

* use singular for banner

docs/settings/banners-settings.asciidoc

@@ -0,0 +1,35 @@
+[role="xpack"]
+[[banners-settings-kb]]
+=== Banner settings in {kib}
+++++
+<titleabbrev>Banners settings</titleabbrev>
+++++
+
+Banners are disabled by default. You need to manually configure them in order to use the feature.
+
+You can configure the `xpack.banners` settings in your `kibana.yml` file.
+
+[[general-banners-settings-kb]]
+==== General banner settings
+
+[cols="2*<"]
+|===
+
+| `xpack.banners.placement`
+| Set to `header` to enable the header banner. Defaults to `disabled`.
+
+| `xpack.banners.textContent`
+| The text to display inside the banner, either plain text or Markdown.
+
+| `xpack.banners.textColor`
+| The color for the banner text. Defaults to `#8A6A0A`.
+
+| `xpack.banners.backgroundColor`
+| The color of the banner background. Defaults to `#FFF9E8`.
+
+|===
+
+[NOTE]
+====
+The `banners` plugin is a https://www.elastic.co/subscriptions[subscription feature]
+====

docs/settings/settings-xkb.asciidoc

@@ -12,6 +12,7 @@ For more {kib} configuration settings, see <<settings>>.
 
 include::alert-action-settings.asciidoc[]
 include::apm-settings.asciidoc[]
+include::banners-settings.asciidoc[]
 include::dev-settings.asciidoc[]
 include::graph-settings.asciidoc[]
 include::infrastructure-ui-settings.asciidoc[]

docs/setup/settings.asciidoc

@@ -671,6 +671,7 @@ Valid locales are: `en`, `zh-CN`, `ja-JP`. *Default: `en`*
 
 include::{kib-repo-dir}/settings/alert-action-settings.asciidoc[]
 include::{kib-repo-dir}/settings/apm-settings.asciidoc[]
+include::{kib-repo-dir}/settings/banners-settings.asciidoc[]
 include::{kib-repo-dir}/settings/dev-settings.asciidoc[]
 include::{kib-repo-dir}/settings/graph-settings.asciidoc[]
 include::{kib-repo-dir}/settings/fleet-settings.asciidoc[]