fix: clarify user login for patrons

- Closes rero#3789.

Co-Authored-by: Pascal Repond <pascal.repond@rero.ch>

rero_ils/theme/templates/rero_ils/login_user.html

@@ -47,7 +47,7 @@ <h3 class="card-title my-4">{{_('Log in to account') }}</h3>
       name="login_user_form">
       {{form.hidden_tag()}}
       {{form_errors(form)}}
-      {{ render_field(form.email, icon="fa fa-user", autofocus=True, errormsg=False, placeholder=_("E-mail or username")) }}
+      {{ render_field(form.email, icon="fa fa-user", autofocus=True, errormsg=False, placeholder=_("Card number, username, or email")) }}
       {{ render_field(form.password, icon="fa fa-lock", errormsg=False) }}
       <button type="submit" class="btn btn-primary btn-lg btn-block mb-2"><i class="fa fa-sign-in"></i>
         {{_('Log In')}}</button>