Add Rack::TempfileReaper to tests and docs

guides/source/rails_on_rack.md

@@ -126,6 +126,7 @@ use ActionDispatch::ContentSecurityPolicy::Middleware
 use Rack::Head
 use Rack::ConditionalGet
 use Rack::ETag
+use Rack::TempfileReaper
 run MyApp::Application.routes
 ```
 
@@ -300,6 +301,10 @@ Much of Action Controller's functionality is implemented as Middlewares. The fol
 
 * Adds ETag header on all String bodies. ETags are used to validate cache.
 
+**`Rack::TempfileReaper`**
+
+* Cleans up tempfiles used to buffer multipart requests.
+
 TIP: It's possible to use any of the above middlewares in your custom Rack stack.
 
 Resources

railties/test/application/middleware_test.rb

@@ -45,7 +45,8 @@ module ApplicationTests
         "ActionDispatch::ContentSecurityPolicy::Middleware",
         "Rack::Head",
         "Rack::ConditionalGet",
-        "Rack::ETag"
+        "Rack::ETag",
+        "Rack::TempfileReaper"
       ], middleware
     end
 
@@ -69,7 +70,8 @@ module ApplicationTests
         "ActionDispatch::Callbacks",
         "Rack::Head",
         "Rack::ConditionalGet",
-        "Rack::ETag"
+        "Rack::ETag",
+        "Rack::TempfileReaper"
       ], middleware
     end