Add link to suggest edits

Author: bkeepers

_config.yml

@@ -20,3 +20,8 @@ defaults:
       path: ""
     values:
       layout: article
+
+branch: gh-pages
+
+github:
+  repository_nwo: github/open-source-handbook

_layouts/article.html

@@ -1,5 +1,9 @@
 <h1>{{ page.title }}</h1>
 
+<a href="https://github.com/{{ site.github.repository_nwo }}/edit/{{ site.branch }}/{{ page.path }}">
+  Suggest edits
+</a>
+
 {{ content }}
 
 {% assign previous = site.pages | where: "next", page.path | first %}