feat: Document ignoreLayersType in koa integration (#14060)

Documents getsentry/sentry-javascript#16553,
released with
https://github.com/getsentry/sentry-javascript/releases/tag/9.29.0

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>

Author: 2 people

docs/platforms/javascript/common/configuration/integrations/koa.mdx

@@ -26,6 +26,29 @@ Sentry.init({
 });
 ```
 
+## Options
+
+### `ignoreLayersType`
+
+Requires SDK version `9.29.0` or higher.
+
+_Type: `Array<'middleware' | 'router'>`_
+
+An array of Koa layer types to ignore when creating spans. This allows you to filter out specific types of middleware or router spans from being sent to Sentry.
+
+```javascript
+// To ignore middleware spans
+const Sentry = require('@sentry/node');
+
+Sentry.init({
+  integrations: [
+    Sentry.koaIntegration({
+      ignoreLayersType: ['middleware']
+    })
+  ],
+})
+```
+
 ## Supported Versions
 
 - `koa`: `^2.0.0`