remove obsoleted instruction from icon themes' README
remove obsoleted instruction from icon themes' README

Change-Id: Id6e7f7dea6284af1b94c2616c9c83f88448115be

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core