doc: fix typo in ipsec-secgw guide
doc: fix typo in ipsec-secgw guide

Fixes: 02dc5b7d58c7 ("doc: update ipsec-secgw guide and release notes")
Cc: stable@dpdk.org

Signed-off-by: David Marchand <f28529695cfa9e3e1eb84e7072aa626af4abb18e@redhat.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk