Cleanup: fix some typos in code comment

Signed-off-by: Guangming Wang <guangming.wang@daocloud.io>

import.go

@@ -86,7 +86,7 @@ func WithImportCompression() ImportOpt {
 
 // Import imports an image from a Tar stream using reader.
 // Caller needs to specify importer. Future version may use oci.v1 as the default.
-// Note that unreferrenced blobs may be imported to the content store as well.
+// Note that unreferenced blobs may be imported to the content store as well.
 func (c *Client) Import(ctx context.Context, reader io.Reader, opts ...ImportOpt) ([]images.Image, error) {
 	var iopts importOpts
 	for _, o := range opts {