README: update links LICENSE extension

Signed-off-by: Guspan Tanadi <[email protected]>

Author: guspan-tanadi

README.md

@@ -16,4 +16,4 @@ See [CODEOWNERS](.github/CODEOWNERS).
 
 This project is licensed under the [BSD-3-clause
 License](https://spdx.org/licenses/BSD-3-Clause.html). See
-[LICENSE.txt](LICENSE.txt) for the full license text.
+[LICENSE](LICENSE) for the full license text.