nixos-modules/microvm/optimization: update doc

thanks to @nagisa

nixos-modules/microvm/optimization.nix

@@ -17,16 +17,15 @@ in
   options.microvm.optimize = {
     enable = lib.mkOption {
       description = lib.mdDoc ''
-        Enables some optimizations to closure size and startup time:
-          - disables X libraries for non-graphical VMs
+        Enables some optimizations by default to closure size and startup time:
           - defaults documentation to off
           - defaults to using systemd in initrd
-          - builds qemu without graphics or sound for non-graphical qemu VMs
+          - use systemd-networkd
+          - disables systemd-network-wait-online
+          - disables NixOS system switching if the host store is not mounted
 
         This takes a few hundred MB off the closure size, including qemu,
-        allowing for putting microvms inside Docker containers.
-
-        May cause more build time by e.g. rebuilding qemu.
+        allowing for putting MicroVMs inside Docker containers.
       '';
 
       type = lib.types.bool;