Add contributors section

Author: arimatakao

README.md

@@ -162,3 +162,8 @@ This project uses the following third-party libraries:
 - PTerm (https://github.com/pterm/pterm) - Licensed under the MIT
 - gopdf (https://github.com/signintech/gopdf) - Licensed under the MIT
 - go-epub (https://github.com/go-shiori/go-epub) - Licensed under the MIT
+
+## Contributors
+
+- [arimatakao](https://github.com/arimatakao)
+- [wolandark](https://github.com/wolandark)