docs(README): add 'toss' logo image (#299)

Author: sukvvon

README-ko_kr.md

@@ -97,3 +97,10 @@ packages/
 ## 라이선스
 
 MIT © Viva Republica, Inc. 자세한 내용은 [LICENSE](./LICENSE)를 참고하세요.
+
+<a title="Toss" href="https://toss.im">
+  <picture>
+    <source media="(prefers-color-scheme: dark)" srcset="https://static.toss.im/logos/png/4x/logo-toss-reverse.png">
+    <img alt="Toss" src="https://static.toss.im/logos/png/4x/logo-toss.png" width="100">
+  </picture>
+</a>

README.md

@@ -97,3 +97,10 @@ We welcome contributions from everyone! Please check our contribution guide.
 ## License
 
 MIT © Viva Republica, Inc. See [LICENSE](./LICENSE) for details.
+
+<a title="Toss" href="https://toss.im">
+  <picture>
+    <source media="(prefers-color-scheme: dark)" srcset="https://static.toss.im/logos/png/4x/logo-toss-reverse.png">
+    <img alt="Toss" src="https://static.toss.im/logos/png/4x/logo-toss.png" width="100">
+  </picture>
+</a>