Core: Fix langAlias not being passed to Shiki rehype plugin

.changeset/shaggy-lines-love.md

@@ -0,0 +1,5 @@
+---
+'fumadocs-core': patch
+---
+
+Fix `langAlias` not being passed to Shiki rehype plugin

packages/core/src/mdx-plugins/rehype-code.ts

@@ -134,6 +134,7 @@ export function rehypeCode(
       langs:
         options.langs ??
         (options.lazy ? ['ts', 'tsx'] : Object.keys(bundledLanguages)),
+      langAlias: options.langAlias,
     },
   );