Update README.md

Author: k-miyake

README.md

@@ -3,5 +3,5 @@
 This repository is a clone of https://github.com/nuxt/learn.nuxt.com and is a Japanese version project.\
 Some of the content will be created in Japanese before the original.\
 We have received permission from [@antfu](https://github.com/antfu).\
-Special thanks to [@antfu](https://github.com/antfu) 💚
+Special thanks to [@antfu](https://github.com/antfu) 💚.\
 This repository is sponsored by [NuxtLabs Japan](https://zenadvisor.io/nuxtlabs-japan).