Update "getting started" link to Atlas

The current link 404's, but this fixes it.

Thanks to copyedt on Twitter: https://twitter.com/copyedt/status/620807196259958785

website/source/intro/getting-started/next.html.markdown

@@ -17,7 +17,7 @@ the [documentation](/docs). The documentation is less of a guide and
 more of a reference of all the overall features and options of Packer.
 
 If you're interested in learning more about how Packer fits into the
-HashiCorp ecosystem of tools, read our [Atlas getting started overview](https://atlas.hashicorp.com/help/getting-started/getting-started-overview).
+HashiCorp ecosystem of tools, read our [Atlas getting started overview](https://atlas.hashicorp.com/help/intro/getting-started).
 
 As you use Packer more, please voice your comments and concerns on
 the [mailing list or IRC](/community). Additionally, Packer is