Add "Accessing route data" section in getStaticPaths with routePattern

src/content/docs/en/reference/routing-reference.mdx

@@ -170,6 +170,40 @@
 <h1>{id}: {post.name}</h1>
 ```
 
+### `routePattern`
+
+<p>
+
+**Type:** `string` <br />
+<Since v="5.15.0" />
+</p>
+
+A string parameter [`getStaticPaths()`](#getstaticpaths) to access the current [`routePattern`](/en/reference/api-reference/#routepattern).
+
+This provides data from the [Astro render context](https://docs.astro.build/en/reference/api-reference/) that would not otherwise be available within the scope of `getStaticPaths()` and can be useful to calculate the `params` and `props` for each page route.
+
+`routePattern` always reflects the original dynamic segment definition in the file path (e.g. `/[...locale]/[slug]`), unlike `params`, which are explicit values for a page (e.g. `/fr/post-1/`).
+
+```astro title="src/pages/[...locale]/[files]/[slug].astro"
+---
+export async function getStaticPaths({ routePattern }) {
+  // Calculate the appropriate params based on the routePattern
+  const params = [];
+
+  // e.g. read route pattern and translate the [files] segment to all locales
+  if (routePattern.includes("[files]")) {
+    locales.forEach((locale) => {
+      params.push({ files: getMessage(locale, "files") });
+    });
+  }
+
+  return { params };
+}
+
+const { page } = Astro.props;
+---
+```
+
 ### `paginate()`
 
 <p>