[spec] Fix the GitHub URL to edit the spec files.

[Cherry-picked b4ce684]

Author: sjrd

Diff for: docs/_spec/_layouts/default.yml

@@ -27,7 +27,7 @@
   <header class="hidden-print">
     <nav id="chapters">
       <a href="{{site.baseurl}}/" title="Table of Contents">Scala {{ site.thisScalaVersion }}</a>
-      <a id="github" href="https://github.com/scala/scala/tree/2.13.x/spec"><img src="public/images/[email protected]" alt="Edit at GitHub"></a>
+      <a id="github" href="https://github.com/lampepfl/dotty/tree/main/docs/_spec"><img src="public/images/[email protected]" alt="Edit at GitHub"></a>
       {% assign sorted_pages = site.pages | sort:"name" %}
       {% for post in sorted_pages %}
         {% if post.chapter >= 0 %}

Diff for: docs/_spec/_layouts/toc.yml

@@ -20,7 +20,7 @@
   <div id="header-main">
   <img id="scala-logo" src="public/images/scala-spiral-white.png" />
   <span id="title">Scala Language Specification</span>
-  <a id="github" href="https://github.com/scala/scala/tree/{{ site.thisScalaVersion }}.x/spec"><img src="public/images/[email protected]" alt="Edit at GitHub"></a>
+  <a id="github" href="https://github.com/lampepfl/dotty/tree/main/docs/_spec"><img src="public/images/[email protected]" alt="Edit at GitHub"></a>
   </div>
   <div id="header-sub">Version {{ site.thisScalaVersion }}</div>
 </header>