fix start/end (#1731)

Add an optional extended description…

aspnet/performance/caching/response.rst

@@ -106,7 +106,8 @@ Instead of duplicating ``ResponseCache`` settings on many controller action attr
 Setting up a cache profile:
 
 .. literalinclude:: response/sample/src/ResponseCacheSample/Startup.cs
-  :lines: 29-45
+  :start-after: Use this method to add services to the container.
+  :end-before: // This
   :emphasize-lines: 5-15
   :dedent: 8
   :language: c#

aspnet/performance/caching/response/sample/src/ResponseCacheSample/wwwroot/_references.js

@@ -1,2 +1,7 @@
 /// <autosync enabled="true" />
+/// <reference path="../gulpfile.js" />
 /// <reference path="js/site.js" />
+/// <reference path="lib/bootstrap/dist/js/bootstrap.js" />
+/// <reference path="lib/jquery/dist/jquery.js" />
+/// <reference path="lib/jquery-validation/dist/jquery.validate.js" />
+/// <reference path="lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js" />