title: Change label "username" to "account number" in WooCommerce registration
body: <p>I am trying to change "username" label on WooCommerce registration form to "account number" label. So when the data is exported, account numbers will become usernames.</p>
  
  <p>I copied the following code and change it bit:</p>
  
  <pre><code>function woocommerce_reg_form() { 
  
  add_filter( 'gettext', 'woocommerce_register_text' ); 
  add_filter( 'ngettext', 'register_text' ); 
  function register_text( $translating ) { 
      $translated = str_ireplace( 'Username or Email Address', 'Acc', $translating ); 
      return $translated; 
  } 
  
  add_action( 'woocommerce_registration_form' ); 
  </code></pre>
  
  <p>But it is giving me errors and doesn't work. What I am doing wrong? Please guide me.</p>