Update cpp/ql/src/Likely Bugs/Memory Management/PointerOverflow.qhelp

Co-Authored-By: Jonas Jensen <jbj@github.com>

Author: rdmarsh2

cpp/ql/src/Likely Bugs/Memory Management/PointerOverflow.qhelp

@@ -22,7 +22,7 @@ To check whether an index <code>i</code> is less than the length of an array,
 simply compare these two numbers as unsigned integers: <code>i &lt; ARRAY_LENGTH</code>. 
 If the length of the array is defined as the difference between two pointers 
 <code>ptr</code> and <code>p_end</code>, write <code>i &lt; p_end - ptr</code>.
-If i is <code>signed</code>, cast it to <code>unsigned</code> 
+If <code>i</code> is signed, cast it to unsigned
 in order to guard against negative <code>i</code>. For example, write 
 <code>(size_t)i &lt; p_end - ptr</code>.
 </p>