navigation: add a RSS link

Co-Authored-by: Igor Milhit <igor@milhit.ch>

assets/scss/_fonts.scss

@@ -9,10 +9,11 @@ html, body {
 }
 
 code,
+figure p,
 .footnotes,
 .footnote-ref,
-figure p,
 .main-footer,
+nav,
 .posts-list footer {
   font-size: $font-size-small;
 }

layouts/partials/header.html

@@ -8,6 +8,13 @@
     <nav>
       <a href="{{ .Site.BaseURL }}blog">Blog</a> /
       <a href="{{ .Site.BaseURL }}categories">Catégories</a>
+      {{ if .IsNode }}
+        / <a href="{{ .Permalink }}index.xml"><span class="smallcaps">rss</a>
+      {{ end }}
+      {{ if .IsPage }}
+        / <a href="{{ .Site.BaseURL }}index.xml"><span class="smallcaps">rss</a>
+      {{ end }}
+
     </nav>
   </section>
 </header>