Add a link to the github repository

_layouts/base.html

@@ -69,6 +69,14 @@ <h1>{{ page.title }}</h1>
           <li><a href="/{{ relative_path }}">English</a></li>
           <li><a href="/ja/{{ relative_path }}">日本語</a></li>
         </ul>
+        <p class="contribute">
+           {% if page.language == "en" %}
+             {% assign source_path = page.url | remove: ".html" | append: ".md" %}
+           {% else %}
+             {% assign source_path = page.url | prepend: "/_po" | remove: ".html" | append: ".po" %}
+           {% endif %}
+           {% assign source_path = source_path | prepend: "https://github.com/droonga/droonga.org/blob/gh-pages" %}
+           <a href="{{ source_path }}">{{ page.label_edit }}</a></p>
         <p class="copyright">&copy; {{ site.copyright_year }} <a href="https://github.com/droonga">Droonga Project</a></p>
       </div>
     </footer>

_layouts/en.html

@@ -2,5 +2,6 @@
 layout: base
 language: en
 path_prefix: /
+label_edit: If you see any typo, please feel free to send pull requests!
 ---
 {{ content }}

_layouts/ja.html

@@ -2,5 +2,6 @@
 layout: base
 language: ja
 path_prefix: /ja/
+label_edit: 誤記や未訳箇所を見つけた場合は、お気軽にプルリクエストをお送りください!
 ---
 {{ content }}