Updated AWS template README

- Use specific release URLs for the "Launch Stack" buttons to avoid template config caching on the AWS side
- Updated list of settings for the advanced stack

Fixes #53. Closes #54

aws-cloudformation/README.md

@@ -36,7 +36,7 @@ If you have an existing AWS account (with billing and an SSH key pair), just cli
 **WARNING:** if you have an existing sandbox server created before Dec 31, 2019 (v1), **DO NOT UPGRADE**.  
 See [v2.0.0](https://github.com/docksal/sandbox-server/releases/tag/v2.0.0) release notes.
 
-[![Launch Basic Stack](https://cdn.rawgit.com/buildkite/cloudformation-launch-stack-button-svg/master/launch-stack.svg)](https://console.aws.amazon.com/cloudformation/home#/stacks/new?stackName=docksal-sandbox-server&templateURL=https://s3.us-east-2.amazonaws.com/docksal-aws-templates/sandbox-server/v3/basic.json)
+[![Launch Basic Stack](https://cdn.rawgit.com/buildkite/cloudformation-launch-stack-button-svg/master/launch-stack.svg)](https://console.aws.amazon.com/cloudformation/home#/stacks/new?stackName=docksal-sandbox-server&templateURL=https://docksal-aws-templates.s3.us-east-2.amazonaws.com/sandbox-server/v3.3.0/basic.json) (v3.3.0)
 
 You will be prompted for:
 
@@ -60,15 +60,15 @@ If you have an existing AWS account (with billing and an SSH key pair), just cli
 **WARNING:** if you have an existing sandbox server created before Dec 31, 2019 (v1), **DO NOT UPGRADE**.  
 See [v2.0.0](https://github.com/docksal/sandbox-server/releases/tag/v2.0.0) release notes.
 
-[![Launch Advanced Stack](https://cdn.rawgit.com/buildkite/cloudformation-launch-stack-button-svg/master/launch-stack.svg)](https://console.aws.amazon.com/cloudformation/home#/stacks/new?stackName=docksal-sandbox-server&templateURL=https://s3.us-east-2.amazonaws.com/docksal-aws-templates/sandbox-server/v3/advanced.json)
+[![Launch Advanced Stack](https://cdn.rawgit.com/buildkite/cloudformation-launch-stack-button-svg/master/launch-stack.svg)](https://console.aws.amazon.com/cloudformation/home#/stacks/new?stackName=docksal-sandbox-server&templateURL=https://docksal-aws-templates.s3.us-east-2.amazonaws.com/sandbox-server/v3.3.0/advanced.json) (v3.3.0)
 
 You will be prompted for a few required and optional settings.
 
 - Basic: Required
   - Resource type (`ec2` vs `spot`)
+  - Instance architecture (`amd64` vs `arm64`)
   - Instance type (primary)
-  - Instance type 2 (spot only)
-  - Instance type 3 (spot only)
+  - Instance type 2 (`spot` mode only)
   - SSH key
   - Availability zone
 - VPC/Network: Optional