docs(pipelines): remove notice for lack of CodePipeline V2 support (#34133)

### Reason for this change

CDK Pipelines added support for CodePipeline V2 in https://github.com/aws/aws-cdk/releases/tag/v2.189.0.

### Description of changes

Removed the notice about lack of CodePipeline V2 support in CDK Pipelines documentation.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: alexpulver

packages/aws-cdk-lib/pipelines/README.md

@@ -11,8 +11,7 @@ cluster directly: use CDK file assets with CloudFormation Init for instances, or
 CDK container assets for ECS clusters instead.
 
 Give the CDK Pipelines way of doing things a shot first: you might find it does
-everything you need. If you need more control, or if you need `v2` support from
-`aws-codepipeline`, we recommend you drop down to using the `aws-codepipeline`
+everything you need. If you need more control, we recommend you drop down to using the `aws-codepipeline`
 construct library directly.
 
 > This module contains two sets of APIs: an **original** and a **modern** version of