updated README

Author: mammad2c

README.md

@@ -57,6 +57,12 @@ also if you are running gitlab on your own server you can change `url`:
 
 **NOTE**: `url` should be without `/` at the end.
 
+### Gitlab compatibility:
+
+This script relay on Gitlab API V4. So if your self hosted Gitlab server is outdated, you should update it to use this script.
+
+[https://docs.gitlab.com/ee/api/v3_to_v4.html](https://docs.gitlab.com/ee/api/v3_to_v4.html)
+
 ---
 
 # Inspiration