Update mkdocs.yml

Author: qwertygc

mkdocs.yml

@@ -110,6 +110,8 @@ extra:
   social:
     - icon: fontawesome/brands/github
       link: https://github.com/ccbogel/QualCoder
+    - icon: fontawesome/brands/facebook
+      link: https://www.facebook.com/groups/1251478525589873
 alternate:
   - name: English
     link: /