title: how std::u8string will be different from std::string?
body: <p>If I have a string:</p>
  
  <pre><code>std::string s = u8"你好";
  </code></pre>
  
  <p>and in C++20,</p>
  
  <pre><code>std::u8string s = u8"你好";
  </code></pre>
  
  <p>how <code>std::u8string</code> will be different from <code>std::string</code>?</p>