Update core/src/main/java/com/scalar/db/api/AuthAdmin.java

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: komamitsu

core/src/main/java/com/scalar/db/api/AuthAdmin.java

@@ -404,7 +404,7 @@ interface User {
     boolean isSuperuser();
   }
 
-  /** Represents a role. */
+  /** Represents a role, including its granted member roles. */
   interface Role {
     /** Returns the role name. */
     String getName();