fix 'edit page' link

_layouts/default.html

@@ -41,8 +41,12 @@ common-js:
     {{ content }}
     <hr/>
     <footer class="container">
-        <p>&copy; 2013–2019. The go-ethereum Authors. | <a href="https://github.com/ethereum/go-ethereum/blob/gh-pages/{{ page.name }}">Edit this page</a></p>
+      {%- capture gh_link -%}
-</p>
+      https://github.com/ethereum/go-ethereum/blob/gh-pages/
+      {%- if page.collection -%}{{ site.collections_dir }}/{%- endif -%}
+      {{- page.path -}}
+      {%- endcapture -%}
+      <p>&copy; 2013–2019. The go-ethereum Authors. <a href="{{ gh_link }}">Edit this page.</a></p>
     </footer>
   </body>
 </html>