Merge pull request #347 from liulanzheng/update_build_doc

update doc for buildkit

Author: BigVan

README.md

@@ -52,9 +52,8 @@ Accelerated Container Image is a __non-core__ sub-project of containerd.
 
     What's more, standalone userspace image-convertor is faster than embedded image-convertor when used with our [customized libext2fs](https://github.com/data-accelerator/e2fsprogs). See [USERSPACE_CONVERTOR](https://github.com/containerd/accelerated-container-image/blob/main/docs/USERSPACE_CONVERTOR.md) for more details.
 
-* [buildkit for overlaybd](https://github.com/data-accelerator/buildkit) (Experimental)
-
-    It is a customized buildkit for overlaybd images. It fetches the data of base images on demand without pulling whole data and uses overlaybd writable layer to build new layers.
+* buildkit
+    BuildKit officially supports overlaybd image building since v0.22. Benefiting from the on-demand loading of the base image and the high-performance writable layer, image build speeds can be significantly improved. Compared to the image conversion approach, this method saves the time previously required for conversion. See more at [Overlaybd](https://github.com/moby/buildkit/blob/master/docs/overlaybd.md).
 
 * [overlaybd - turboOCIv1](docs/TURBO_OCI.md)
 

docs/QUICKSTART.md

@@ -263,7 +263,7 @@ sudo /opt/overlaybd/snapshotter/convertor -r registry.hub.docker.com/library/red
 
 ## Image build
 
-Overlaybd images can be efficiently built from overlaybd images by using the [customized buildkit](https://github.com/data-accelerator/buildkit).
+Overlaybd images can be efficiently built from overlaybd images by using the [buildkit](https://github.com/moby/buildkit) v0.22+.
 
 ### Install
 
@@ -280,12 +280,12 @@ sudo make install
 First, make sure the overlaybd-snapshotter and overlaybd-tcmu running.
 
 ```bash
-# use containerd worker with overlaybd snapshotter
-buildkitd --containerd-worker-snapshotter=overlaybd --oci-worker=false --containerd-worker=true
+# use oci worker with overlaybd snapshotter
+buildkitd --oci-worker-snapshotter=overlaybd --oci-worker-proxy-snapshotter-path=/run/overlaybd-snapshotter/overlaybd.sock
 ```
 
 Then, write your Dockerfile and run buildctl to build images.
-The `FROM` if Dockerfile must be an overlaybd image.
+The `FROM` image in Dockerfile must be an overlaybd image.
 
 ```bash
 buildctl build \