Fix typo in denormalization section (#95)

README.md

@@ -877,7 +877,7 @@ Denormalization attempts to improve read performance at the expense of some writ
 
 Once data becomes distributed with techniques such as [federation](#federation) and [sharding](#sharding), managing joins across data centers further increases complexity.  Denormalization might circumvent the need for such complex joins.
 
-In most systems, reads can heavily number writes 100:1 or even 1000:1.  A read resulting in a complex database join can be very expensive, spending a significant amount of time on disk operations.
+In most systems, reads can heavily outnumber writes 100:1 or even 1000:1.  A read resulting in a complex database join can be very expensive, spending a significant amount of time on disk operations.
 
 ##### Disadvantage(s): denormalization