Merge pull request #1111 from aaronlehmann/golint-comments

Correct two golint comment issues

digest/tarsum.go

@@ -6,7 +6,7 @@ import (
 	"regexp"
 )
 
-// TarSumRegexp defines a regular expression to match tarsum identifiers.
+// TarsumRegexp defines a regular expression to match tarsum identifiers.
 var TarsumRegexp = regexp.MustCompile("tarsum(?:.[a-z0-9]+)?\\+[a-zA-Z0-9]+:[A-Fa-f0-9]+")
 
 // TarsumRegexpCapturing defines a regular expression to match tarsum identifiers with

registry/storage/walk.go

@@ -8,7 +8,7 @@ import (
 	storageDriver "github.com/docker/distribution/registry/storage/driver"
 )
 
-// SkipDir is used as a return value from onFileFunc to indicate that
+// ErrSkipDir is used as a return value from onFileFunc to indicate that
 // the directory named in the call is to be skipped. It is not returned
 // as an error by any function.
 var ErrSkipDir = errors.New("skip this directory")