Add icons for Debian, Ubuntu and openSUSE downloads

_includes/download-stable.html

@@ -61,11 +61,11 @@
     <p>
       Several GNU/Linux distributions have official packages for Dynare:
       <ul>
-        <li><a href="https://packages.debian.org/sid/dynare">Debian</a></li>
-        <li><a href="https://launchpad.net/ubuntu/+source/dynare">Ubuntu</a></li>
+        <li><a href="https://packages.debian.org/sid/dynare"><i class="fa-brands fa-debian"></i> Debian</a></li>
+        <li><a href="https://launchpad.net/ubuntu/+source/dynare"><i class="fa-brands fa-ubuntu"></i> Ubuntu</a></li>
         <li><a href="https://community.linuxmint.com/software/view/dynare">Linux Mint</a></li>
         <li><a href="https://aur.archlinux.org/packages/dynare/">Arch Linux</a></li>
-        <li><a href="https://software.opensuse.org/package/dynare">openSUSE</a></li>
+        <li><a href="https://software.opensuse.org/package/dynare"><i class="fa-brands fa-suse"></i> openSUSE</a></li>
       </ul>
       Note that on Debian, Ubuntu and Linux Mint, you also need to install the
       <tt>dynare-matlab</tt> package if you want MATLAB support.