Merge pull request #3740 from justinsb/comment_vfs_readtree

Automatic merge from submit-queue.

Clarify comment on ReadTree

util/pkg/vfs/vfs.go

@@ -60,7 +60,7 @@ type Path interface {
 	// ReadDir lists the files in a particular Path
 	ReadDir() ([]Path, error)
 
-	// ReadTree lists all files in the subtree rooted at the current Path
+	// ReadTree lists all files (recursively) in the subtree rooted at the current Path
 	ReadTree() ([]Path, error)
 }