document generic <class>_<target> idiom in gbuild
document generic <class>_<target> idiom in gbuild

Change-Id: I8b746c3786eda42c3c91c104daee2018ba20b975

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