Add a resource to plugins in Vue.js (#2820)

Talks about what are plugins, shows how to create a simple vue.js plugin, Add directives, mixins, filters, and how to accept options.

content/roadmaps/105-vue/content/101-advanced-topics/112-plugins.md

@@ -4,3 +4,4 @@ Plugins are self-contained code that usually add app-level functionality to Vue.
 
 <ResourceGroupTitle>Free Content</ResourceGroupTitle>
 <BadgeLink colorScheme='blue' badgeText='Official Docs' href='https://vuejs.org/guide/reusability/plugins.html'>Plugins in Vue.js</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.linode.com/docs/guides/how-to-write-vue-js-plugins/'>How to Write Your Own Vue.js Plugin</BadgeLink>