Grammar fix

Replaced "less" with "fewer"

cppguide.html

@@ -341,7 +341,7 @@ of Includes</a> for rules about when to #include a header.</p>
 
 <div class="summary">
 <p>Define functions inline only when they are small, say, 10
-lines or less.</p>
+lines or fewer.</p>
 </div>
 
 <div class="stylebody">