Update api-design.md (MicrosoftDocs#449)

Add missing 'to'.

docs/best-practices/api-design.md

@@ -38,7 +38,7 @@ Here are some of the main design principles of RESTful APIs using HTTP:
     {"orderId":1,"orderValue":99.90,"productId":1,"quantity":1}
     ```
 
-- REST APIs use a uniform interface, which helps to decouple the client and service implementations. For REST APIs built on HTTP, the uniform interface includes using standard HTTP verbs perform operations on resources. The most common operations are GET, POST, PUT, PATCH, and DELETE. 
+- REST APIs use a uniform interface, which helps to decouple the client and service implementations. For REST APIs built on HTTP, the uniform interface includes using standard HTTP verbs to perform operations on resources. The most common operations are GET, POST, PUT, PATCH, and DELETE. 
 
 - REST APIs use a stateless request model. HTTP requests should be independent and may occur in any order, so keeping transient state information between requests is not feasible. The only place where information is stored is in the resources themselves, and each request should be an atomic operation. This constraint enables web services to be highly scalable, because there is no need to retain any affinity between clients and specific servers. Any server can handle any request from any client. That said, other factors can limit scalability. For example, many web services write to a backend data store, which may be hard to scale out. (The article [Data Partitioning](./data-partitioning.md) describes strategies to scale out a data store.)