feat: point Edit Page link directly to GitHub editor

Previously, it pointed to the file viewer.

Close #1224

layouts/partials/edit_page.html

@@ -1,6 +1,6 @@
 {{ if site.Params.edit_page.repo_url | and (index site.Params.edit_page.editable .Type) | and (ne .Params.editable false) | or .Params.editable }}
 <p class="edit-page">
-  <a href="{{site.Params.edit_page.repo_url}}/blob/{{site.Params.edit_page.repo_branch | default "master"}}/content/{{.File.Path}}">
+  <a href="{{site.Params.edit_page.repo_url}}/edit/{{site.Params.edit_page.repo_branch | default "master"}}/content/{{.File.Path}}">
     <i class="fas fa-pen pr-2"></i>{{ i18n "edit_page" | default "Edit this page" }}
   </a>
 </p>