Discordのアイコンを修正

README.md

@@ -6,7 +6,7 @@
 [![Test Coverage](https://api.codeclimate.com/v1/badges/ba10b596888853bc3f83/test_coverage)](https://codeclimate.com/github/annict/annict/test_coverage)
 [![Code Climate](https://codeclimate.com/github/annict/annict/badges/gpa.svg)](https://codeclimate.com/github/annict/annict)
 [![Ruby Style Guide](https://img.shields.io/badge/code_style-standard-brightgreen.svg)](https://github.com/testdouble/standard)
-[![Discord](https://camo.githubusercontent.com/b12a95e20b7ca35f918c0ab5103fe56b6f44c067/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f636861742d6f6e253230646973636f72642d3732383964612e737667)](https://discord.gg/PVJRUKP)
+[![Discord](https://img.shields.io/discord/1044830617860317184?label=Discord&color=5865F2)](https://discord.gg/PVJRUKP)
 
 [Annict](https://annict.com) は、見たアニメを記録したり友達に共有したりできるアニメ視聴記録サービスです。