Update readme.md

Small typo: witch for which.

readme.md

 # REST version of Spring PetClinic Sample Application (spring-framework-petclinic extend ) [![Build Status](https://travis-ci.org/spring-petclinic/spring-petclinic-rest.png?branch=master)](https://travis-ci.org/spring-petclinic/spring-petclinic-rest/)
 
 This backend version of the Spring Petclinic application only provides a REST API. **There is no UI**.
-The [spring-petclinic-angular project](https://github.com/spring-petclinic/spring-petclinic-angular) is a Angular front-end application witch consumes the REST API.
+The [spring-petclinic-angular project](https://github.com/spring-petclinic/spring-petclinic-angular) is a Angular front-end application which consumes the REST API.
 
 ## Understanding the Spring Petclinic application with a few diagrams