Merge pull request rails#43542 from maaslalani/ml-doc-hostauthorization

Link to Host Authorization guides on `blocked_host` page

Author: rafaelfranca

actionpack/lib/action_dispatch/middleware/templates/rescues/blocked_host.html.erb

@@ -4,4 +4,5 @@
 <main role="main" id="container">
   <h2>To allow requests to <%= @host %> make sure it is a valid hostname (containing only numbers, letters, dashes and dots), then add the following to your environment configuration:</h2>
   <pre>config.hosts &lt;&lt; "<%= @host %>"</pre>
+  <p>For more details view: <a href="https://guides.rubyonrails.org/configuring.html#actiondispatch-hostauthorization">the Host Authorization guide</a></p>
 </main>

actionpack/lib/action_dispatch/middleware/templates/rescues/blocked_host.text.erb

@@ -3,3 +3,5 @@ Blocked host: <%= @host %>
 To allow requests to <%= @host %> make sure it is a valid hostname (containing only numbers, letters, dashes and dots), then add the following to your environment configuration:
 
   config.hosts << "<%= @host %>"
+
+For more details on host authorization view: https://guides.rubyonrails.org/configuring.html#actiondispatch-hostauthorization