Address review comments

pkg/api/annotations.go

@@ -222,7 +222,7 @@ func PatchAnnotation(c *m.ReqContext, cmd dtos.PatchAnnotationsCmd) Response {
 	items, err := repo.Find(&annotations.ItemQuery{AnnotationId: annotationID, OrgId: c.OrgId})
 
 	if err != nil || len(items) == 0 {
-		return Error(500, "Could not find annotation to update", err)
+		return Error(404, "Could not find annotation to update", err)
 	}
 
 	existing := annotations.Item{

pkg/api/dtos/annotations.go

@@ -23,11 +23,11 @@ type UpdateAnnotationsCmd struct {
 }
 
 type PatchAnnotationsCmd struct {
-	Id       int64    `json:"id"`
-	Time     int64    `json:"time"`
-	Text     string   `json:"text"`
-	Tags     []string `json:"tags"`
-	TimeEnd  int64    `json:"timeEnd"`
+	Id      int64    `json:"id"`
+	Time    int64    `json:"time"`
+	Text    string   `json:"text"`
+	Tags    []string `json:"tags"`
+	TimeEnd int64    `json:"timeEnd"`
 }
 
 type DeleteAnnotationsCmd struct {