Update openbmc-systemd.md link

openbmc-systemd.md is moving under architecture/ as part of
https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/26325

26325 should merge before this is merged.

Change-Id: Ifd3bedd900312a152efe16f2324871061f47968c
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
1 file changed