Explain meaning of the code very well and Remove confusion. [ci skip]

Code like `render(topics) => render("topics/topic")` adds confusion
for the readers. On first impression, that code feels like hash kind
of data, but it's not. So make it more clear and meaningful.

actionview/lib/action_view/helpers/cache_helper.rb

@@ -69,11 +69,11 @@ module CacheHelper
       #   render 'comments/comments'
       #   render('comments/comments')
       #
-      #   render "header" => render("comments/header")
+      #   render "header" translates to render("comments/header")
       #
-      #   render(@topic)         => render("topics/topic")
-      #   render(topics)         => render("topics/topic")
-      #   render(message.topics) => render("topics/topic")
+      #   render(@topic)         translates to render("topics/topic")
+      #   render(topics)         translates to render("topics/topic")
+      #   render(message.topics) translates to render("topics/topic")
       #
       # It's not possible to derive all render calls like that, though.
       # Here are a few examples of things that can't be derived:

guides/source/caching_with_rails.md

@@ -198,11 +198,11 @@ render "comments/comments"
 render 'comments/comments'
 render('comments/comments')
 
-render "header" => render("comments/header")
+render "header" translates to render("comments/header")
 
-render(@topic)         => render("topics/topic")
-render(topics)         => render("topics/topic")
-render(message.topics) => render("topics/topic")
+render(@topic)         translates to render("topics/topic")
+render(topics)         translates to render("topics/topic")
+render(message.topics) translates to render("topics/topic")
 ```
 
 On the other hand, some calls need to be changed to make caching work properly.