Added PATCH verb end point for annotation op

Added new PATCH verb annotation endpoint

Removed unwanted fmt

Added test cases for PATCH verb annotation endpoint

Fixed formatting issue

Check arr len before proceeding

Updated doc to include PATCH verb annotation endpt

pkg/api/dtos/annotations.go

@@ -22,6 +22,14 @@ type UpdateAnnotationsCmd struct {
 	TimeEnd  int64    `json:"timeEnd"`
 }
 
+type PatchAnnotationsCmd struct {
+	Id       int64    `json:"id"`
+	Time     int64    `json:"time"`
+	Text     string   `json:"text"`
+	Tags     []string `json:"tags"`
+	TimeEnd  int64    `json:"timeEnd"`
+}
+
 type DeleteAnnotationsCmd struct {
 	AlertId      int64 `json:"alertId"`
 	DashboardId  int64 `json:"dashboardId"`