change class overview proper position

src/mechanize/history.cr

@@ -1,8 +1,8 @@
 require "./page"
 
+class Mechanize
   # This class represents the history of http response you sent.
   # If you send a request, mechanize saves the history.
-class Mechanize
   class History
     # max page size history can save. default is 100.
     # as same as `agent.max_history`.

src/mechanize/http/agent.cr

@@ -5,6 +5,7 @@ require "../history"
 
 class Mechanize
   module HTTP
+    # This class handles web interation mechanize made.
     class Agent
       property request_headers : ::HTTP::Headers
       property context : Mechanize?

src/mechanize/page.cr

@@ -2,10 +2,10 @@ require "./file"
 require "./utils/element_matcher"
 require "./page/link"
 
+class Mechanize
   # This class represents the result of http response.
   # If you send a request, it returns the instance of `Mechanize::Page`.
   # You can get status code, title, and page body, and search html node using css selector from page instance.
-class Mechanize
   class Page < Mechanize::File
     include Mechanize::ElementMatcher