Put external dependencies into dedicated directories

tubio-frontend-nuxt-app/plugins/README.md

@@ -0,0 +1,7 @@
+# PLUGINS
+
+**This directory is not required, you can delete it if you don't want to use it.**
+
+This directory contains Javascript plugins that you want to run before mounting the root Vue.js application.
+
+More information about the usage of this directory in [the documentation](https://nuxtjs.org/guide/plugins).