Add Docker Actions badge

Author: SakaDream

README.md

@@ -1,6 +1,7 @@
 # Actix-web REST API with JWT
 
 ![Cross-platform CICD](https://github.com/SakaDream/actix-web-rest-api-with-jwt/workflows/Cross-platform%20CICD/badge.svg)
+![Docker CICD](https://github.com/SakaDream/actix-web-rest-api-with-jwt/workflows/Docker%20CICD/badge.svg)
 
 A simple CRUD backend app using Actix-web, Diesel and JWT