fix ext

Author: jcs090218

README.md

@@ -90,4 +90,4 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-See [`LICENSE`](./LICENSE.txt) for details.
+See [`LICENSE`](./LICENSE) for details.