add donation info in metadata.json

as suggested in #332

unite@hardpixel.eu/metadata.json

@@ -6,5 +6,8 @@
   "gettext-domain": "unite",
   "version": 71,
   "name": "Unite",
-  "description": "Unite is a GNOME Shell extension which makes a few layout tweaks to the top panel and removes window decorations to make it look like Ubuntu Unity Shell.\n\n- Adds window buttons to the top panel for maximized windows.\n- Shows current window title in the app menu for maximized windows.\n- Removes titlebars on maximized windows.\n- Hides window controls on maximized windows with headerbars.\n- Moves the date to the right, reduces panel spacing and removes dropdown arrows.\n- Moves legacy tray icons to the top panel.\n- Moves notifications to the right.\n- Hides activities button.\n- Adds desktop name to the top panel.\n\nThis extension depends on some Xorg utilities. To install them:\n- Debian/Ubuntu: apt install x11-utils\n- Fedora/RHEL: dnf install xprop\n- Fedora Silverblue: rpm-ostree install xprop\n- Arch: pacman -S xorg-xprop\n\n*Settings are provided to enable/disable or customize the available tweaks.\n* Since version 2 applications on wayland with client side decorations are supported using CSS."
+  "description": "Unite is a GNOME Shell extension which makes a few layout tweaks to the top panel and removes window decorations to make it look like Ubuntu Unity Shell.\n\n- Adds window buttons to the top panel for maximized windows.\n- Shows current window title in the app menu for maximized windows.\n- Removes titlebars on maximized windows.\n- Hides window controls on maximized windows with headerbars.\n- Moves the date to the right, reduces panel spacing and removes dropdown arrows.\n- Moves legacy tray icons to the top panel.\n- Moves notifications to the right.\n- Hides activities button.\n- Adds desktop name to the top panel.\n\nThis extension depends on some Xorg utilities. To install them:\n- Debian/Ubuntu: apt install x11-utils\n- Fedora/RHEL: dnf install xprop\n- Fedora Silverblue: rpm-ostree install xprop\n- Arch: pacman -S xorg-xprop\n\n*Settings are provided to enable/disable or customize the available tweaks.\n* Since version 2 applications on wayland with client side decorations are supported using CSS.",
+  "donations": {
+    "github": "jonian"
+  }
 }