Add Laravel Korea Facebook group link

Author: yhbyun

README.md

@@ -293,6 +293,7 @@ Inspired by [ziadoz/awesome-php](https://github.com/ziadoz/awesome-php)
 * [Laravel Taiwan](http://laravel.tw/) ([Facebook group](https://www.facebook.com/groups/laravel.tw/))
 * [Laravel Spanish](http://laraveles.com/foro/)
 * [Laravel Korea](http://laravel.co.kr/)
+* [Laravel Korea Facebook group](https://www.facebook.com/groups/laravelkorea/)
 
 #### Meetups
 * [All Meetups](http://laravel.meetup.com/)
@@ -320,4 +321,4 @@ Found an awesome package, blog, video etc.? Send me a PR!
 * Please make an individual pull request for each suggestion
 * Use the following format for resources: \[Resource\]\(URL\)
 * Use the following format for packages: \[Package\]\(URL\) - Short description
-* New categories or improvements to the existing categorisation are welcome
+* New categories or improvements to the existing categorisation are welcome