Update readme

README.md

@@ -1,5 +1,5 @@
 # xwayland-satellite
-xwayland-satellite grants rootless Xwayland integration to any Wayland compositor implementing xdg_wm_base.
+xwayland-satellite grants rootless Xwayland integration to any Wayland compositor implementing xdg_wm_base and viewporter.
 This is particularly useful for compositors that (understandably) do not want to go through implementing support for rootless Xwayland themselves.
 
 ## Dependencies
@@ -22,3 +22,16 @@ cargo run
 xwayland-satellite can be built with systemd support - simply add `-F systemd` to your build command - i.e. `cargo build --release -F systemd`.  
 With systemd support, satellite will send a state change notification when Xwayland has been initialized, allowing for having services dependent on satellite's startup.  
 An example service file is located in `resources/xwayland-satellite.service` - be sure to replace the `ExecStart` line with the proper location before using it. It can be placed in a systemd user unit directory (i.e. `$XDG_CONFIG_HOME/systemd/user` or `/etc/systemd/user`), and be launched and enabled with `systemctl --user enable --now xwayland-satellite`. It will be started when the `graphical-session.target` is reached, which is likely after your compositor is started if it supports systemd.
+
+## Wayland protocols used
+The host compositor **must** implement the following protocols/interfaces for satellite to function:
+- Core interfaces (wl_output, wl_surface, wl_compositor, etc)
+- xdg_shell (xdg_wm_base, xdg_surface, xdg_popup, xdg_toplevel)
+- wp_viewporter - used for scaling
+
+Additionally, satellite can *optionally* take advantage of the following protocols:
+- Linux dmabuf
+- XDG activation
+- XDG foreign
+- Pointer constraints
+- Tablet input