Update README.md

Signed-off-by: Sebastiaan Meijer <sebastiaan@passthroughpo.st>

README.md

@@ -1,2 +1,23 @@
 # VFIO-Tools
 A collection of tools and scripts that aim to make PCI passthrough a little easier.
+
+## libvirt_hooks
+
+### QEMU hook helper
+This contains a hook-helper for libvirt which allows easier per-VM hooks.  
+Simply drop the `qemu` file in `$SYSCONFDIR/libvirt/hooks/` (usually `/etc/libvirt/hooks`) and you're ready to add hooks.  
+You can have a virtually limitless number of hook scripts per VM and per hook call, just keep in mind that a failed hook will prevent a VM from starting.  
+The way to add hooks is as follows:  
+- Create a file in a path matching this structure:
+```
+$SYSCONFDIR/libvirt/hooks/qemu.d/vm_name/hook_name/state_name/yourhook.conf
+```
+- You can put anything you like in the hook, as long as you make sure you start your hook with a hashbang (i.e. `#!/bin/bash`).
+- When you're done setting up your hook, run `chmod +x` on your hook file to make it executable.
+- If you've added the `qemu` hook helper file for the first time, you need to restart libvirt in order for it to be detected.
+
+### switch_displays.sh
+This hook allows you to automatically switch your monitor input to your VM's display.  
+To achieve this you need to have `ddcutil` installed and working and you need a DDC/CI capable monitor.  
+For a more detailed explanation and write-up, check out https://passthroughpo.st
+