[Orgmode] moving past state changes into logbook drawer?

[Michael Gilbert]

Hi —

I am just now transitioning to logging state changes into a logbook drawer. But 
I have legacy agenda files with hundreds of lines that were not put into that 
drawer. Does anyone know of a convenient way to move all the past state changes 
into the suitable drawer? If that in the manual, I'm afraid I missed it.

TIA!

— Michael