Merge pull request #19 from jciskey/patch-2

Fix typos

docs/sorting_calculated_fields.rst

@@ -2,12 +2,12 @@ How to enable sorting on calculated fields?
 ===========================================================
 
 Django adds sorting capabilities on fields which are attributes on the models.
-When you add a calculated field Django doesn't know how to do a :code:`order_by`, so it doesn't a sorting capability on that field.
+When you add a calculated field Django doesn't know how to do a :code:`order_by`, so it doesn't add sorting capability on that field.
 
-If you want to add sorting on a calculated field, you have to tell Django, what to pass to :code:`order_by`. You can do this by setting
+If you want to add sorting on a calculated field, you have to tell Django what to pass to :code:`order_by`. You can do this by setting the
 :code:`admin_order_field` attribute on the calculated field method.
 
-You start from the admin you wrote in the pervious chapter (:doc:`optimize_queries`).::
+You start from the admin you wrote in the previous chapter (:doc:`optimize_queries`).::
 
     hero_count.admin_order_field = '_hero_count'
     villain_count.admin_order_field = '_villain_count'