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/checks.txt

@@ -325,8 +325,8 @@ Security
 
 The security checks do not make your site secure. They do not audit code, do
 intrusion detection, or do anything particularly complex. Rather, they help
-perform an automated, low-hanging-fruit checklist. They help you remember the
-simple things that improve your site's security.
+perform an automated, low-hanging-fruit checklist, that can help you to improve
+your site's security.
 
 Some of these checks may not be appropriate for your particular deployment
 configuration. For instance, if you do your HTTP to HTTPS redirection in a load