improve comment

src/mechanize.cr

@@ -298,7 +298,7 @@ class Mechanize
 
   # set basic auth credentials.
   # ```
-  # # make download.html whose content is http://example.com's html.
+  # # set an auth credential with a specific url.
   # agent.add_auth("http://example.com", "username", "password")
   # ```
   def add_auth(uri : String, user : String, pass : String)

src/mechanize/http/agent.cr

@@ -163,7 +163,7 @@ class Mechanize
 
       # set basic auth credentials.
       # ```
-      # # make download.html whose content is http://example.com's html.
+      # # set an auth credential with a specific url.
       # agent.add_auth("http://example.com", "username", "password")
       # ```
       def add_auth(uri : String, user : String, pass : String)

src/mechanize/http/auth_store.cr

@@ -8,6 +8,7 @@ class Mechanize
         @auth_accounts = Hash(URI, Hash(String, Array(String))).new
       end
 
+      # set an auth credential with a specific url.
       def add_auth(uri : String | URI, user : String, pass : String, realm : String? = nil, domain : String? = nil)
         target_uri = uri.dup
         unless uri.is_a?(URI)
@@ -28,7 +29,6 @@ class Mechanize
         end
       end
 
-      ##
       # Returns true if credentials exist for the +challenges+ from the server at
       # +uri+.