[__package_update_index] add support for openwrt

cdist/conf/type/__package_update_index/explorer/type

@@ -27,6 +27,7 @@ else
         debian|ubuntu|devuan) echo "apt" ;;
         archlinux) echo "pacman" ;;
         alpine) echo "apk" ;;
+        openwrt) echo "opkg" ;;
         *)
             echo "Don't know how to manage packages on: $os" >&2
             exit 1

cdist/conf/type/__package_update_index/gencode-remote

@@ -52,6 +52,10 @@ case "$type" in
         echo "apk update"
         echo "apk package database updated." >>"$__messages_out"
         ;;
+    opkg)
+        echo "opkg update"
+        echo "opkg package database updated." >>"$__messages_out"
+        ;;
     *)
         echo "Don't know how to manage packages for type: $type" >&2
         exit 1

cdist/conf/type/__package_update_index/man.rst

@@ -26,6 +26,7 @@ type
     * apt for Debian
     * yum for Red Hat
     * pacman for Arch Linux
+    * opkg for OpenWrt
 
 maxage
     Available for package manager apt and pacman, max time in seconds since