PEL: Add sysinfo UserData section to README
PEL: Add sysinfo UserData section to README

Mention the UserData section that is added to every BMC PEL that
contains system information in the README where it lists the sections
created.

Signed-off-by: Matt Spinler <c000c989d08c98662d98f15448f11de169feb92d@us.ibm.com>
Change-Id: If36396817f438bc97785a0a60c18e11c7c276ac1

openbmc/phosphor-logging,openbmc/phosphor-logging,openbmc/phosphor-logging,openbmc/phosphor-logging