fix(docs): doc improvements (openai#1364)

Author: stainless-bot

README.md

@@ -521,7 +521,7 @@ The context manager is required so that the response will reliably be closed.
 
 ### Making custom/undocumented requests
 
-This library is typed for convenient access the documented API.
+This library is typed for convenient access to the documented API.
 
 If you need to access undocumented endpoints, params, or response properties, the library can still be used.