chore: add dup4 link

Dup4 · Dup4 · commit bb4319490c67 · 2023-09-20T13:35:58.000+08:00
Signed-off-by: Dup4 &lt;lyuzhi.pan@gmail.com&gt;
diff --git a/README.md b/README.md
@@ -37,3 +37,5 @@ See the usage in the [unit test](./test/result_test.cc)
 ## License
 
 [MIT](./LICENSE) License © 2022 - PRESENT [Dup4][dup4]
+
+[dup4]: https://github.com/Dup4
