Fixed #30573 -- Rephrased documentation to avoid words that minimise the involved difficulty.

This patch does not remove all occurrences of the words in question.
Rather, I went through all of the occurrences of the words listed
below, and judged if they a) suggested the reader had some kind of
knowledge/experience, and b) if they added anything of value (including
tone of voice, etc). I left most of the words alone. I looked at the
following words:

- simply/simple
- easy/easier/easiest
- obvious
- just
- merely
- straightforward
- ridiculous

Thanks to Carlton Gibson for guidance on how to approach this issue, and
to Tim Bell for providing the idea. But the enormous lion's share of
thanks go to Adam Johnson for his patient and helpful review.

docs/ref/class-based-views/mixins-single-object.txt

@@ -63,7 +63,7 @@ Single object mixins
         with access to individual objects should be prevented from obtaining
         this list, setting ``query_pk_and_slug`` to ``True`` will help prevent
         the guessing of URLs as each URL will require two correct,
-        non-sequential arguments. Simply using a unique slug may serve the same
+        non-sequential arguments. Using a unique slug may serve the same
         purpose, but this scheme allows you to have non-unique slugs.
 
         .. _insecure direct object reference: https://www.owasp.org/index.php/Top_10_2013-A4-Insecure_Direct_Object_References
@@ -128,7 +128,7 @@ Single object mixins
     .. method:: get_slug_field()
 
         Returns the name of a slug field to be used to look up by slug. By
-        default this simply returns the value of :attr:`slug_field`.
+        default this returns the value of :attr:`slug_field`.
 
 
 ``SingleObjectTemplateResponseMixin``