Apply suggestions from code review

Co-authored-by: Ben Ahmady <32935794+subatoi@users.noreply.github.com>

Author: geoffw0

swift/ql/src/queries/Security/CWE-1333/ReDoS.qhelp

@@ -2,14 +2,14 @@
 <qhelp>
   <include src="ReDoSIntroduction.inc.qhelp" />
   <example>
-    <p>Consider this regular expression:</p>
+    <p>Consider the following regular expression:</p>
     <sample language="swift">
 /^_(__|.)+_$/</sample>
     <p>
       Its sub-expression <code>"(__|.)+"</code> can match the string
       <code>"__"</code> either by the first alternative <code>"__"</code> to the
       left of the <code>"|"</code> operator, or by two repetitions of the second
-      alternative <code>"."</code> to the right. Thus, a string consisting of an
+      alternative <code>"."</code> to the right. Therefore, a string consisting of an
       odd number of underscores followed by some other character will cause the
       regular expression engine to run for an exponential amount of time before
       rejecting the input.

swift/ql/src/queries/Security/CWE-1333/ReDoSIntroduction.inc.qhelp

@@ -31,7 +31,7 @@
     <p>
       Modify the regular expression to remove the ambiguity, or ensure that the
       strings matched with the regular expression are short enough that the
-      time-complexity does not matter.
+      time complexity does not matter.
     </p>
   </recommendation>
 </qhelp>