docs(facebook): added readme

Author: ritz078

packages/embed-plugin-facebook/Readme.md

@@ -0,0 +1,37 @@
+# embed-plugin-facebook
+
+A plugin that can be used to embed facebook posts/videos.
+
+## Installation
+```
+npm i -S embed-js embed-plugin-facebook
+```
+
+### CDN
+
+https://unpkg.com/embed-plugin-facebook
+
+## Usage
+
+[![Edit embed.js - facebook](https://codesandbox.io/static/img/play-codesandbox.svg)](https://codesandbox.io/s/7jx90or24x)
+
+```js
+import EmbedJS from 'embed-js'
+import facebook from 'embed-plugin-facebook'
+
+const x = new EmbedJS({
+  input: document.getElementById('element'),
+  plugins: [
+  facebook({
+    regex: /facebookPostRegex/gi, // in case you want to define a custom regex
+    template(args) {
+      // optional template
+    }
+   })
+ ]
+})
+```
+When you click on the link URL, it redirects you to the post URL.
+
+### License
+MIT @ Ritesh Kumar