feat: added placeholder example

Author: ezhil56x

examples/01-basic/11-placeholder/App.tsx

@@ -5,15 +5,18 @@ import { useCreateBlockNote } from "@blocknote/react";
 import { locales } from "@blocknote/core";
 
 export default function App() {
+  // Set the user locale.
+  const userLocale = "en";
+
   const placeholder = "This is a custom placeholder";
 
   // Creates a new editor instance.
   const editor = useCreateBlockNote({
     dictionary: {
-      ...locales.en,
+      ...locales[userLocale],
       placeholders: {
-        ...locales.en.placeholders,
-        default: placeholder ?? locales.en.placeholders.default,
+        ...locales[userLocale].placeholders,
+        default: placeholder ?? locales[userLocale].placeholders.default,
       },
     },
   });