[Doc] The ECAT_FOE_READ_FILE_IND handling explanation may cause misunderstanding for the reader

In the Document EtherCAT Slave Protocol API V5.4  "DOC181005APIV5.4.0.10EN" on the page 94-95 , we can see the the explanation of the ECAT_FOE_READ_FILE_IND call handling, however, some values  in the text may cause misunderstanding for the reader.

1) Field "ulExt.Seq" is mentioned in the document, maybe it should mean, that the field ulExt has a sub-field Seg, but in the repository https://subversion01.hilscher.local/svn/netXSupport/Examples/NXSLFW/projects/NXSLFWECSV5/trunk/NXHX90-JTAG, at revision: 11334 , in the file Hil_Packet.h , the field ulExt in the structure HIL_PACKET_HEADER_T does not have any subfield Seq , it is just uint32_t.

2) The values of the field ulExt are mentioned in the reduced form as FIRST, MIDDLE and LAST. In the practice, it should be used full-form values HIL_PACKET_SEQ_FIRST, HIL_PACKET_SEQ_MIDDLE and HIL_PACKET_SEQ_LAST consequently. Besides, this full-form values are mentioned in the section " 6.11.2.1 SoE write request "