Fix typo in list of conventions in docs/design/README.md (#3815)

Author: gosar

docs/design/README.md

@@ -62,7 +62,7 @@ None
   [java.util.Optional](https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html).
 * [Completable Future Usage](UseOfCompletableFuture.md) - Conventions
   governing the use of
-* [java.util.concurrent.CompletableFuture](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html).
+  [java.util.concurrent.CompletableFuture](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html).
 * [APIReference](APIReference.md) - Conventions used for API references
 
 **Rejected**