Improve the deprecation message for using subclass of Rails::Application to start the Rails server

railties/CHANGELOG.md

@@ -57,7 +57,7 @@
 
     *bogdanvlviv*
 
-*   Deprecate support of use `Rails::Application` subclass to start Rails server.
+*   Deprecate support for using a `Rails::Application` subclass to start Rails server.
 
     *Yuji Yaginuma*
 

railties/lib/rails/commands/server/server_command.rb

@@ -27,7 +27,7 @@ def app
         app = super
         if app.is_a?(Class)
           ActiveSupport::Deprecation.warn(<<-MSG.squish)
-            Use `Rails::Application` subclass to start the server is deprecated and will be removed in Rails 6.0.
+            Using `Rails::Application` subclass to start the server is deprecated and will be removed in Rails 6.0.
             Please change `run #{app}` to `run Rails.application` in config.ru.
           MSG
         end

railties/test/application/server_test.rb

@@ -29,7 +29,7 @@ def teardown
       server.app
 
       log = File.read(Rails.application.config.paths["log"].first)
-      assert_match(/DEPRECATION WARNING: Use `Rails::Application` subclass to start the server is deprecated/, log)
+      assert_match(/DEPRECATION WARNING: Using `Rails::Application` subclass to start the server is deprecated/, log)
     end
 
     test "restart rails server with custom pid file path" do