Update documentation for DefaultCredentialsProvider.create (#5009)

* Update documentation for DefaultCredentialsProvider.create

* Update DefaultCredentialsProvider.java

Author: zoewangg

core/auth/src/main/java/software/amazon/awssdk/auth/credentials/DefaultCredentialsProvider.java

@@ -74,8 +74,9 @@ private DefaultCredentialsProvider(Builder builder) {
     }
 
     /**
-     * Create an instance of the {@link DefaultCredentialsProvider} using the default configuration. Configuration can be
-     * specified by creating an instance using the {@link #builder()}.
+     * Returns the singleton instance of the {@link DefaultCredentialsProvider} using the default configuration. 
+     * Configuration can be specified by creating an instance using the {@link #builder()}. If you want to 
+     * create a new instance, use {@link #builder()} instead.
      */
     public static DefaultCredentialsProvider create() {
         return DEFAULT_CREDENTIALS_PROVIDER;