Add badges

Author: danog

README.md

@@ -1,6 +1,9 @@
 # tg-file-decoder
 
 ![build](https://github.com/danog/tg-file-decoder/workflows/build/badge.svg)
+[![Psalm coverage](https://shepherd.dev/github/danog/tg-file-decoder/coverage.svg)](https://shepherd.dev/github/danog/tg-file-decoder)
+[![Psalm level 1](https://shepherd.dev/github/danog/tg-file-decoder/level.svg)](https://shepherd.dev/github/danog/tg-file-decoder)
+![License](https://img.shields.io/github/license/danog/tg-file-decoder)
 
 Decode and encode [Telegram bot API file IDs](https://core.telegram.org)!