updates documentation

Author: ahmarsuhail

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/auth/MarshalledCredentialProvider.java

@@ -40,6 +40,7 @@
  */
 @InterfaceAudience.Private
 @InterfaceStability.Unstable
+@SuppressWarnings("deprecation")
 public class MarshalledCredentialProvider extends
     AbstractSessionCredentialsProvider {
 

hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/aws_sdk_upgrade.md

@@ -17,7 +17,7 @@
 This document explains the upcoming work for upgrading S3A to AWS SDK V2.
 This work is tracked in [HADOOP-18073](https://issues.apache.org/jira/browse/HADOOP-18073).
 
-## Why do we want to upgrade?
+## Why the upgrade?
 
 - Moving to SDK V2 will provide performance benefits.
 For example, the [transfer manager for SDKV2](https://aws.amazon.com/blogs/developer/introducing-amazon-s3-transfer-manager-in-the-aws-sdk-for-java-2-x/)