ES.2: Fix wrong code logic in the example (#1999)

CppCoreGuidelines.md

@@ -10269,7 +10269,7 @@ The more traditional and lower-level near-equivalent is longer, messier, harder
             is.read(s, maxstring);
             res[elemcount++] = s;
         }
-        nread = &elemcount;
+        *nread = elemcount;
         return res;
     }