Update cache docs

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

docs/reference/buildx_build.md

@@ -201,10 +201,17 @@ single-platform build result to `docker images`.
 --cache-from=[NAME|type=TYPE[,KEY=VALUE]]
 ```
 
-Use an external cache source for a build. Supported types are `registry` and `local`.
-The `registry` source can import cache from a cache manifest or (special) image
-configuration on the registry. The `local` source can import cache from local
-files previously exported with `--cache-to`.
+Use an external cache source for a build. Supported types are `registry`,
+`local` and `gha`.
+
+- [`registry` source](https://github.com/moby/buildkit#registry-push-image-and-cache-separately)
+can import cache from a cache manifest or (special) image configuration on the
+registry.
+- [`local` source](https://github.com/moby/buildkit#local-directory-1) can
+import cache from local files previously exported with `--cache-to`.
+- [`gha` source](https://github.com/moby/buildkit#github-actions-cache-experimental)
+can import cache from a previously exported cache with `--cache-to` in your
+GitHub repository
 
 If no type is specified, `registry` exporter is used with a specified reference.
 
@@ -217,18 +224,27 @@ $ docker buildx build --cache-from=user/app:cache .
 $ docker buildx build --cache-from=user/app .
 $ docker buildx build --cache-from=type=registry,ref=user/app .
 $ docker buildx build --cache-from=type=local,src=path/to/cache .
+$ docker buildx build --cache-from=type=gha .
 ```
 
+More info about cache exporters and available attributes: https://github.com/moby/buildkit#export-cache
+
 ### <a name="cache-to"></a> Export build cache to an external cache destination (--cache-to)
 
 ```
 --cache-to=[NAME|type=TYPE[,KEY=VALUE]]
 ```
 
-Export build cache to an external cache destination. Supported types are `registry`,
-`local` and `inline`. Registry exports build cache to a cache manifest in the
-registry, local exports cache to a local directory on the client and inline writes
-the cache metadata into the image configuration.
+Export build cache to an external cache destination. Supported types are
+`registry`, `local`, `inline` and `gha`.
+
+- [`registry` type](https://github.com/moby/buildkit#registry-push-image-and-cache-separately) exports build cache to a cache manifest in the registry.
+- [`local` type](https://github.com/moby/buildkit#local-directory-1) type
+exports cache to a local directory on the client.
+- [`inline` type](https://github.com/moby/buildkit#inline-push-image-and-cache-together)
+type writes the cache metadata into the image configuration.
+- [`gha` type](https://github.com/moby/buildkit#github-actions-cache-experimental)
+type exports cache through the [Github Actions Cache service API](https://github.com/tonistiigi/go-actions-cache/blob/master/api.md#authentication).
 
 `docker` driver currently only supports exporting inline cache metadata to image
 configuration. Alternatively, `--build-arg BUILDKIT_INLINE_CACHE=1` can be used
@@ -236,8 +252,8 @@ to trigger inline cache exporter.
 
 Attribute key:
 
-- `mode` - Specifies how many layers are exported with the cache. “min” on only
-exports layers already in the final build stage, “max” exports layers for
+- `mode` - Specifies how many layers are exported with the cache. `min` on only
+exports layers already in the final build stage, `max` exports layers for
 all stages. Metadata is always exported for the whole build.
 
 **Examples**
@@ -247,8 +263,11 @@ $ docker buildx build --cache-to=user/app:cache .
 $ docker buildx build --cache-to=type=inline .
 $ docker buildx build --cache-to=type=registry,ref=user/app .
 $ docker buildx build --cache-to=type=local,dest=path/to/cache .
+$ docker buildx build --cache-to=type=gha .
 ```
 
+More info about cache exporters and available attributes: https://github.com/moby/buildkit#export-cache
+
 ### <a name="allow"></a> Allow extra privileged entitlement (--allow)
 
 ```