docs(pack-images): change stack id

Author: duanhongyi

README.md

@@ -6,22 +6,22 @@ This repository is responsible for building and publishing images that builds
 with [Cloud Native Buildpacks'](https://buildpacks.io)
 [`pack`](https://github.com/buildpacks/pack) command.
 
-* [drycc/pack:20](https://hub.docker.com/r/drycc/pack/tags/) - A CNB
-  compatible run image based on drycc/pack:20
-* [drycc/pack:20-build](https://hub.docker.com/r/drycc/pack/tags/) - A CNB
-  compatible build image based on drycc/pack:20-build
+* [drycc/pack:bullseye](https://hub.docker.com/r/drycc/pack/tags/) - A CNB
+  compatible run image based on drycc/pack:bullseye
+* [drycc/pack:bullseye-build](https://hub.docker.com/r/drycc/pack/tags/) - A CNB
+  compatible build image based on drycc/pack:bullseye-build
 
 ## Usage
 
-`pack build myapp --builder drycc/buildpacks:20`
+`pack build myapp --builder drycc/buildpacks:bullseye`
 
 ## System
 
 The basic image is based on Debian system, See the table below for system description：
 
-STACK ID     | Buildpacks image                | Operating System
--------------|---------------------------------|---------------------------------
-drycc-20     | registry.drycc.cc/drycc/buildpacks:20   | Debian 11 Bullseye 
+STACK ID        | Buildpacks image                            | Operating System
+----------------|---------------------------------------------|---------------------------------
+drycc-bullseye  | registry.drycc.cc/drycc/buildpacks:bullseye | Debian 11 Bullseye 
 
 The basic layer of buildpack supports custom software sources and custom software.
 For example, if we use alicloud to install libpq-dev, we can add `.deb-list` and `·source-list` files to the project.