docs: implement code-copy

Author: Bart Ledoux

package-lock.json

@@ -35,6 +35,7 @@
     "validate-commit-msg": "^2.14.0",
     "vue-slider-component": "^3.0.31",
     "vuepress": "^1.5.2",
+    "vuepress-plugin-code-copy": "^1.0.6",
     "vuepress-plugin-container": "^2.1.4"
   },
   "dependencies": {