feeds: Add sidn feed

feeds.conf

@@ -5,6 +5,7 @@ src-git routing https://git.lede-project.org/feed/routing.git
 src-git telephony https://git.lede-project.org/feed/telephony.git
 #src-git printing https://github.com/miska/openwrt-printing-packages.git
 src-git openwisp https://github.com/openwisp/openwisp-config.git
+src-git sidn https://github.com/SIDN/sidn_openwrt_pkgs.git
 #src-git video https://github.com/openwrt/video.git
 #src-git targets https://github.com/openwrt/targets.git
 #src-git management https://github.com/openwrt-management/packages.git