chore: change username label

The label was changed to english and arabian mode.

Author: johanseto

openedx/core/djangoapps/user_authn/views/registration_form.py

@@ -531,7 +531,7 @@ def _add_username_field(self, form_desc, required=True):
         """
         # Translators: This label appears above a field on the registration form
         # meant to hold the user's public username.
-        username_label = _(u"Public Username")
+        username_label = _(u"National ID")
 
         username_instructions = _(
             # Translators: These instructions appear on the registration form, immediately