Address eladb's comments on scope.

Still open: naming and command UX

text/0001-cdk-update.md

@@ -5,7 +5,8 @@ tracking issue: https://github.com/aws/aws-cdk-rfcs/issues/1
 
 # CDK Update
 
-Rapid and automatic updates for code-only changes to CDK application stacks.
+Shorten the development iteration speed -- the "edit-compile-test" loop -- for
+CDK applications.
 
 ## Working Backwards
 
@@ -15,11 +16,12 @@ Rapid and automatic updates for code-only changes to CDK application stacks.
 
 ### README
 
-The `cdk update` command accelerates the asset deployments for your CDK
-application during development by inspecting the assets in your application,
-identifying those that can be updated in-place without a full CDK deployment,
-and doing so. It can either do this as an interactive command or by running
-continuously and monitoring the input files.
+The `cdk update` command accelerates the edit-compile-test loop for your CDK
+application during development by inspecting the assets and stack resources in
+your application, identifying those that can be updated in-place without a full
+CloudFormation stack udpate, and doing so using AWS service APIs directly. It
+can either do this as an interactive command or by running continuously and
+monitoring the input files.
 
 For supported construct types (see list, below) the update command will identify
 assets whose content has changed since the publication of the CDK, assemble them
@@ -135,6 +137,11 @@ images.
 - ECS
  - image assets
 
+#### Future Support Plans
+
+- StepFunctions
+- API Gateway models
+
 ### PRESS RELEASE
 
 DATE - AWS announces the `cdk update` command for the AWS CDK toolkit. The