cea/Readme: Fix missing 0x in the boot disk pattern

Fix formatting and some typos

Refs. sysadm-environment#5367

cea/Readme.md

@@ -41,10 +41,11 @@ Then confirm and validate
 **Before rebooting**, in the iLo web interface, get the `Identifier.Durable`
 name: ![durable name](docs/iLo-raid-durable_name.png)
 
-This value must be prefixed with `wwn-` to specify the `BOOT_DISK_ID_PATTERN`
-value in the config file.
 
-For example: `BOOT_DISK_ID_PATTERN: wwn-600063B40DD553802E296F4A1DB5BC1F`
+This value must be prefixed with `wwn-0x` to specify the
+`BOOT_DISK_ID_PATTERN` value in the config file.
+
+For example: `BOOT_DISK_ID_PATTERN: wwn-0x600063B40DD553802E296F4A1DB5BC1F`
 
 ### Preseed generation