Update README.md (#909)

现在2021年了

Author: darrenliuwei

src/README.md

@@ -27,7 +27,7 @@ features:
       Minimal Optimization Efforts
 footer: |
   Released under the <a href="https://opensource.org/licenses/MIT" target="_blank" rel="noopener">MIT License</a><br>
-  Copyright © 2014-2020 Evan You
+  Copyright © 2014-2021 Evan You
 socialIcons:
   - type: GitHub
     link: https://github.com/vuejs/vue-next