release-notes/skiboot-5.3.0-rc1: Fix ReStructured Text syntax
release-notes/skiboot-5.3.0-rc1: Fix ReStructured Text syntax

Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

legoater/skiboot,shenki/skiboot,open-power/skiboot,shenki/skiboot,shenki/skiboot,stewart-ibm/skiboot,stewart-ibm/skiboot,mikey/skiboot,mikey/skiboot,qemu/skiboot,legoater/skiboot,open-power/skiboot,qemu/skiboot,legoater/skiboot,qemu/skiboot,shenki/skiboot,legoater/skiboot,mikey/skiboot,open-power/skiboot,qemu/skiboot,stewart-ibm/skiboot,shenki/skiboot,open-power/skiboot,legoater/skiboot,open-power/skiboot,qemu/skiboot