more explicit error message for docker buildx context error

internal/pipe/docker/docker.go

@@ -235,6 +235,9 @@ files in that dir:
 Previous error:
 %w`, tmp, strings.Join(files, "\n "), err)
 		}
+		if isBuildxContextError(err.Error()) {
+			return fmt.Errorf(`docker buildx not set to default context\nPlease switch with 'docker context use default'\nLearn more at https://goreleaser.com/errors/docker-build`)
+		}
 		return err
 	}
 
@@ -262,6 +265,10 @@ func isFileNotFoundError(out string) bool {
 		strings.Contains(out, ": not found")
 }
 
+func isBuildxContextError(out string) bool {
+	return strings.Contains(out, "buildx to switch to context")
+}
+
 func processImageTemplates(ctx *context.Context, docker config.Docker) ([]string, error) {
 	// nolint:prealloc
 	var images []string

www/docs/errors/docker-build.md

@@ -17,6 +17,14 @@ its root, so you can just `COPY binaryname /bin/binaryname` and etc.
 
 Bellow you can find some **don'ts** as well as what you should **do**.
 
+## `use docker --context=default buildx to switch to context "default"`
+
+The "default" context is a built-in context in "docker buildx", and it is automatically created. This context typically points to the local Docker environment and is used by default for building images. It has to be active for `goreleaser` to build images with "buildx".
+
+You can switch to the default context using `docker context use default`.
+
+This change should be persistant.
+
 ### Don't
 
 Build the binary again.