feat: id for footer (#517)

Added id="footer" just in case someone wants to link there via custom
menus or href="#footer".

Co-authored-by: stueja <jan@jBook.local>
Co-authored-by: Emruz Hossain <hossainemruz@gmail.com>

layouts/partials/footer.html

@@ -64,7 +64,7 @@
   {{ end }}
   {{ $hugoLogo = $hugoLogo.RelPermalink}}
 
-  <footer class="container-fluid text-center align-content-center footer pb-2">
+  <footer id="footer" class="container-fluid text-center align-content-center footer pb-2">
     <div class="container pt-5">
       <div class="row text-left">
         {{ if $navigationEnabled }}