Fix go lint errors

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

metadata/db.go

@@ -190,6 +190,7 @@ func (m *DB) Update(fn func(*bolt.Tx) error) error {
 	return m.db.Update(fn)
 }
 
+// GarbageCollect starts garbage collection
 func (m *DB) GarbageCollect(ctx context.Context) error {
 	lt1 := time.Now()
 	m.wlock.Lock()

metadata/gc.go

@@ -12,10 +12,15 @@ import (
 )
 
 const (
+	// ResourceUnknown specifies an unknown resource
 	ResourceUnknown gc.ResourceType = iota
+	// ResourceContent specifies a content resource
 	ResourceContent
+	// ResourceSnapshot specifies a snapshot resource
 	ResourceSnapshot
+	// ResourceContainer specifies a container resource
 	ResourceContainer
+	// ResourceTask specifies a task resource
 	ResourceTask
 )