chore: adjust the comment (#341)

src/shims.d.ts

@@ -2,7 +2,7 @@ declare interface Window {
   // extend the window
 }
 
-// with vite-plugin-md, markdowns can be treat as Vue components
+// with vite-plugin-md, markdown files can be treated as Vue components
 declare module '*.md' {
   import { type DefineComponent } from 'vue'
   const component: DefineComponent<{}, {}, any>