docs: Fix broken link in readme (#656)

Author: KakeJopulsky

README.md

@@ -197,7 +197,7 @@ public class Example {
 <a name="use-cases"></a>
 # Use Cases
 
-[Examples of common API use cases](USE_CASES.md), such as how to send an email with a transactional template.
+[Examples of common API use cases](use-cases), such as how to send an email with a transactional template.
 
 <a name="announcements"></a>
 # Announcements