feat: Banner (#538)

* add baner

* update banner example

Author: dks333

settings/global.mdx

@@ -416,6 +416,24 @@ Every documentation site requires a `docs.json` file that contains the core conf
   </Expandable>
 </ResponseField>
 
+<ResponseField name="banner" type="object">
+  Banner configurations
+
+  <Expandable title="Banner">
+    <ResponseField name="content" type="string">
+      The content of the banner. This can be a string of text or a markdown string. For example:
+      ```json
+      {
+        "content": "🚀 Banner is live! [Learn more](mintlify.com)"
+      }
+      ```
+    </ResponseField>
+    <ResponseField name="dismissible" type="boolean">
+      Whether the banner is dismissible. Defaults to `false`.
+    </ResponseField>
+  </Expandable>
+</ResponseField>
+
 <ResponseField name="redirects" type="array of object">
 
   <Expandable title="Redirects">