Improve email with confirmation instructions

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/views/devise/mailer/confirmation_instructions.html.erb

-<p>Welcome <%= @resource.email %>!</p>
+<p>Welcome <%= @resource.name %>!</p>
 
-<p>You can confirm your account through the link below:</p>
+<% if @resource.unconfirmed_email.present? %>
+  <p>You can confirm your email (<%= @resource.unconfirmed_email %>) through the link below:</p>
+<% else %>
+  <p>You can confirm your account through the link below:</p>
+<% end %>
 
 <p><%= link_to 'Confirm my account', confirmation_url(@resource, confirmation_token: @resource.confirmation_token) %></p>