Update README.md

vuejs/docs@61274b0#diff-e1d5879ce3e222eb0cdd43051fb8c34c00796467acb091d0b3fa939ee3355cb5

Author: naokie

src/README.md

@@ -27,7 +27,7 @@ features:
       最小限の努力で最適化が可能
 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