change 'Entry' to its full form of 'Index Entry'

Change-Id: I861374e6a5c867f674fb682c6dc0eb6050a372d1
Reviewed-on: https://gerrit.libreoffice.org/12208
Reviewed-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>
Tested-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>