vm: remove doc for non-existing event `monitor-layout-change`
vm: remove doc for non-existing event `monitor-layout-change`

marmarek/qubes-core-admin,marmarek/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin,QubesOS/qubes-core-admin,QubesOS/qubes-core-admin