doc: fix formatting in IP reassembly app guide
doc: fix formatting in IP reassembly app guide

Fixed formatting an extra header was added making it an extra
section when it was not intended.

Fixes: d0dff9ba445e ("doc: sample application user guide")
Cc: stable@dpdk.org

Signed-off-by: Marko Kovacevic <32a723043e16bf2a3185e32c2e613ae1ee55288f@intel.com>
Reviewed-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

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