feat(cloudfront): Distribution is now in Developer Preview (aws#10831)

Move `Distribution` from 'Experimental' to 'Developer Preview'.

----

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

packages/@aws-cdk/aws-cloudfront/README.md

@@ -6,12 +6,12 @@
 | Features | Stability |
 | --- | --- |
 | CFN Resources | ![Stable](https://img.shields.io/badge/stable-success.svg?style=for-the-badge) |
-| Higher level constructs for Distribution | ![Experimental](https://img.shields.io/badge/experimental-important.svg?style=for-the-badge) |
+| Higher level constructs for Distribution | ![Developer Preview](https://img.shields.io/badge/developer--preview-informational.svg?style=for-the-badge) |
 | Higher level constructs for CloudFrontWebDistribution | ![Stable](https://img.shields.io/badge/stable-success.svg?style=for-the-badge) |
 
 > **CFN Resources:** All classes with the `Cfn` prefix in this module ([CFN Resources](https://docs.aws.amazon.com/cdk/latest/guide/constructs.html#constructs_lib)) are always stable and safe to use.
 
-> **Experimental:** Higher level constructs in this module that are marked as experimental are under active development. They are subject to non-backward compatible changes or removal in any future version. These are not subject to the [Semantic Versioning](https://semver.org/) model and breaking changes will be announced in the release notes. This means that while you may use them, you may need to update your source code when upgrading to a newer version of this package.
+> **Developer Preview:** Higher level constructs in this module that are marked as developer preview have completed their phase of active development and are looking for adoption and feedback. While the same caveats around non-backward compatible as Experimental constructs apply, they will undergo fewer breaking changes. Just as with Experimental constructs, these are not subject to the [Semantic Versioning](https://semver.org/) model and breaking changes will be announced in the release notes.
 
 > **Stable:** Higher level constructs in this module that are marked stable will not undergo any breaking changes. They will strictly follow the [Semantic Versioning](https://semver.org/) model.
 

packages/@aws-cdk/aws-cloudfront/package.json

@@ -106,7 +106,7 @@
   "features": [
     {
       "name": "Higher level constructs for Distribution",
-      "stability": "Experimental"
+      "stability": "Developer Preview"
     },
     {
       "name": "Higher level constructs for CloudFrontWebDistribution",