[Cases] Adding cases settings docs (#154672)

This PR adds the new configuration settings to the docs. The
configurations were added in this PR:
#154013

---------

Co-authored-by: lcawl <lcawley@elastic.co>

docs/management/cases/cases.asciidoc

@@ -20,4 +20,5 @@ cases in *{stack-manage-app}*.
 
 * <<setup-cases>>
 * <<manage-cases>>
-* <<add-case-connectors>>
+* <<add-case-connectors>>
+* <<cases-settings>>

docs/settings/cases-settings.asciidoc

@@ -0,0 +1,15 @@
+[[cases-settings]]
+== Cases settings in {kib}
+++++
+<titleabbrev>Cases settings</titleabbrev>
+++++
+
+You do not need to configure any additional settings to use <<cases,cases>> in {kib}.
+To provide greater control over case features, you can configure the following settings in the `kibana.yml` file:
+
+`xpack.cases.files.allowedMimeTypes`::
+The MIME types that you can attach to a case, represented in an array of strings. For example: `['image/tiff','text/csv','application/zip'].`
+The default MIME types are specified in https://github.com/elastic/kibana/blob/{branch}/x-pack/plugins/cases/common/constants/mime_types.ts[mime_types.ts].
+
+`xpack.cases.files.maxSize`::
+The size limit for files that you can attach to a case, represented as the number of bytes. By default, the limit is 10 MiB for images and 100 MiB for all other MIME types. If you specify a value for this setting, it affects all file types.

docs/setup/settings.asciidoc

@@ -622,6 +622,7 @@ 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/cases-settings.asciidoc[leveloffset=+1]
 include::{kib-repo-dir}/settings/enterprise-search-settings.asciidoc[]
 include::{kib-repo-dir}/settings/fleet-settings.asciidoc[]
 include::{kib-repo-dir}/settings/i18n-settings.asciidoc[]