fix typo (#933)

Co-authored-by: Nim Jayawardena <nimjay@google.com>

Author: jackdewan

README.md

@@ -6,7 +6,7 @@
 ![Continuous Integration](https://github.com/GoogleCloudPlatform/microservices-demo/workflows/Continuous%20Integration%20-%20Main/Release/badge.svg)
 
 **Online Boutique** is a cloud-native microservices demo application.
-Online Boutique consists of a 11-tier microservices application. The application is a
+Online Boutique consists of an 11-tier microservices application. The application is a
 web-based e-commerce app where users can browse items,
 add them to the cart, and purchase them.