Fix: DOC: Explain how to opt-out of boot image update in 4.18

Author: Michael Burke

modules/mco-update-boot-images-disable.adoc

@@ -34,4 +34,4 @@ spec:
   managedBootImages: <1>
     machineManagers: []
 ----
-Remove the parameters  that are listed under `machineManagers` and add the `[]` characters to disable the updating of boot images.
+<1> Remove the parameters listed under `machineManagers` and add the `[]` characters to disable boot image updates.