emulator: Add a note about 'BREAKPOINT_INST'
emulator: Add a note about 'BREAKPOINT_INST'

[ci skip]

jbush001/NyuziProcessor,jbush001/NyuziProcessor,jbush001/NyuziProcessor,jbush001/NyuziProcessor,jbush001/NyuziProcessor,jbush001/NyuziProcessor