Fix a typo

requre -> require

cppguide.html

@@ -1505,7 +1505,7 @@ creating objects of user-defined types.</p>
   operations.</li>
 
   <li>Finding the call sites for overloaded operators may
-  requre a search tool that's aware of C++ syntax, rather
+  require a search tool that's aware of C++ syntax, rather
   than e.g. grep.</li>
 
   <li>If you get the argument type of an overloaded operator