add link to source code

src/template.eml.html

@@ -35,7 +35,9 @@ let render_unsafe ~title ~content =
         </div>
         <hr class="featurette-divider">
         <footer class="container">
-          <p>&copy; 2011–2021 OCamlPro &middot;
+          <p>
+            <a href="https://gitlab.ocamlpro.com/OCamlPro/osh">source code</a> &middot;
+            &copy; 2011–2021 OCamlPro &middot;
             <a href="https://twitter.com/ocamlpro">Twitter</a> &middot;
             <a href="https://www.linkedin.com/company/2152404/">LinkedIn</a> &middot;
             <a href="mailto:contact@ocamlpro.com">Email</a> &middot;