fix the description for the `select_all` [ci skip]

guides/source/active_record_querying.md

@@ -1712,10 +1712,10 @@ Client.find_by_sql("SELECT * FROM clients
 
 ### `select_all`
 
-`find_by_sql` has a close relative called `connection#select_all`. `select_all` will retrieve objects from the database using custom SQL just like `find_by_sql` but will not instantiate them. Instead, you will get an array of hashes where each hash indicates a record.
+`find_by_sql` has a close relative called `connection#select_all`. `select_all` will retrieve objects from the database using custom SQL just like `find_by_sql` but will not instantiate them. This method will return an instance of `ActiveRecord::Result` class and calling `to_hash` on this object would return you an array of hashes where each hash indicates a record.
 
 ```ruby
-Client.connection.select_all("SELECT first_name, created_at FROM clients WHERE id = '1'")
+Client.connection.select_all("SELECT first_name, created_at FROM clients WHERE id = '1'").to_hash
 # => [
 #   {"first_name"=>"Rafael", "created_at"=>"2012-11-10 23:23:45.281189"},
 #   {"first_name"=>"Eileen", "created_at"=>"2013-12-09 11:22:35.221282"}