Adding Vietnamese version of IPV6, Rewrite content of README.md

app/context/LanguageContext.tsx

@@ -0,0 +1,41 @@
+"use client";
+
+import React, { createContext, useContext, useEffect, useState } from "react";
+
+export type Lang = "en" | "vi";
+
+interface LanguageContextValue {
+  lang: Lang;
+  setLang: (l: Lang) => void;
+}
+
+const LanguageContext = createContext<LanguageContextValue>({
+  lang: "en",
+  setLang: () => {},
+});
+
+export function LanguageProvider({ children }: { children: React.ReactNode }) {
+  const [lang, setLangState] = useState<Lang>("en");
+
+  useEffect(() => {
+    const saved = localStorage.getItem("ipv6_lang") as Lang | null;
+    if (saved === "vi" || saved === "en") {
+      setLangState(saved);
+    }
+  }, []);
+
+  const setLang = (l: Lang) => {
+    setLangState(l);
+    localStorage.setItem("ipv6_lang", l);
+  };
+
+  return (
+    <LanguageContext.Provider value={{ lang, setLang }}>
+      {children}
+    </LanguageContext.Provider>
+  );
+}
+
+export function useLanguage() {
+  return useContext(LanguageContext);
+}