Add docs about locale

docs/api-reference/data-fetching/get-static-paths.md

@@ -38,8 +38,10 @@ The `paths` key determines which paths will be pre-rendered. For example, suppos
 ```js
 return {
   paths: [
-    { params: { id: '1' } },
-    { params: { id: '2' } }
+    { params: { id: '1' }},
+    { params: { id: '2' }
+      locale: "...",
+    },
   ],
   fallback: ...
 }
@@ -52,6 +54,7 @@ The value for each `params` object must match the parameters used in the page na
 - If the page name is `pages/posts/[postId]/[commentId]`, then `params` should contain `postId` and `commentId`.
 - If the page name uses [catch-all routes](/docs/routing/dynamic-routes.md#catch-all-routes) like `pages/[...slug]`, then `params` should contain `slug` (which is an array). If this array is `['hello', 'world']`, then Next.js will statically generate the page at `/hello/world`.
 - If the page uses an [optional catch-all route](/docs/routing/dynamic-routes.md#optional-catch-all-routes), use `null`, `[]`, `undefined` or `false` to render the root-most route. For example, if you supply `slug: false` for `pages/[[...slug]]`, Next.js will statically generate the page `/`.
+- `locale`: You can also use the `locale` string if you intend to change the active locale.
 
 ### `fallback: false`