style(docs): remove "Back To Top" and link "Contents" header to top

assets/sass/academic/_docs.scss

@@ -206,7 +206,6 @@
   font-size: .875rem;
   font-weight: 600;
   padding-left: calc(1.5rem + 1px);
-  margin-bottom: .5rem;
 }
 
 #TableOfContents {

i18n/en.yaml

@@ -7,7 +7,7 @@
   translation: Table of Contents
 
 - id: on_this_page
-  translation: On this page
+  translation: Contents
 
 - id: back_to_top
   translation: Back to top

layouts/partials/docs_layout.html

@@ -10,16 +10,12 @@
 
     {{ if .Params.toc }}
     <div class="d-none d-xl-block col-xl-2 docs-toc">
-      {{ with (i18n "on_this_page") }}
-      <p class="docs-toc-title">{{.}}</p>
-      {{ end }}
+      <ul class="nav toc-top">
+        <li><a href="#" id="back_to_top" class="docs-toc-title">{{ i18n "on_this_page" }}</a></li>
+      </ul>
 
       {{ .TableOfContents }}
 
-      <ul class="nav toc-top">
-        <li><a href="#">{{ i18n "back_to_top" | default "Back to top" }}</a></li>
-      </ul>
-
       {{ partial "docs_toc_foot.html" . }}
     </div>
     {{ end }}