Update docs for 1.0 release

[mjeffryes]

TODO: break these out into must have/should have/could have

• AWS Getting started page
• CDK specific docs
• Migration pages (from CDK, from CloudFormation, etc)
• Any additional docs
• Docs on PulumiSynthesizer and creating your own
• Docs on remapping resources to AWS Classic

[mjeffryes]

Should also update Readme (Should no longer say preview, review examples)

Can probably defer updates to getting started pages until post launch.