Update README for cross-compiling to Raspbian a bit.
Update README for cross-compiling to Raspbian a bit.

Change-Id: I2741dd3304d85986389a2ae7213cdbb345c6efc6

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