Update README.md
1.5.16 release. http://aws.amazon.com/releasenotes/8545761433555407
1.5.16.1 release. http://aws.amazon.com/releasenotes/8545761433555407
1.5.17 release. http://aws.amazon.com/releasenotes/4784062790863697
1.5.17.1 release. http://aws.amazon.com/releasenotes/PHP/4784062790863697
1.6.0 release. http://aws.amazon.com/releasenotes/2238950844718536
Updated RDS and SWF clients to latest versions
Added support for the CancelUpdateStack operation in the CloudFormation client
Updated SDK for the 1.6.1 release
Fixed a bug in the EC2 client and added the ability to describe and download DB log files to the RDS client
Changelog and version bump for release 1.6.2
Update html-dynamodb_sessions_login.php

typo
Merge pull request #56 from borlak/patch-1

Update typo in html-dynamodb_sessions_login.php