doc: Update pruning design with implement enable/disable options
Instead of passing TRUE/FALSE to a single --enable option
use two flags instead, which IMHO is clearer.
So --enable=TRUE to --enable and --enable=FALSE to --disable
Fixes: https://pagure.io/freeipa/issue/9323
Signed-off-by: Rob Crittenden <rcritten@redhat.com>
Reviewed-By: Mohammad Rizwan <myusuf@redhat.com>
Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>
