Rename the architectures for what Amazon call them

Author: keithduncan

README.md

@@ -98,9 +98,9 @@ make packer
 This will boot and image three AWS EC2 instances in your account’s `us-east-1`
 default VPC:
 
-- Linux amd64
-- Linux arm64
-- Windows amd64
+- Linux (64-bit x86)
+- Linux (64-bit Arm)
+- Windows (64-bit x86)
 
 ## Support Policy
 
@@ -119,9 +119,9 @@ We aim to support new regions within one month of general availability.
 
 We build and deploy the following AMIs to all our supported regions:
 
-- Amazon Linux 2 (x86_64)
-- Amazon Linux 2 (arm64)
-- Windows Server 2019 (x86_64)
+- Amazon Linux 2 (64-bit x86)
+- Amazon Linux 2 (64-bit Arm)
+- Windows Server 2019 (64-bit x86)
 
 ### Buildkite Agent