how to understand "will've"

[harriet_yang]

Dear teachers,

I have a question about this sentence (from Cartwheeling in Thunderstorm by Katherine Rundell):
"We have been notified, madam, that the missing schoolgirl - you will've read about it - may be concealed in your garage."

What does "will've" mean here?

Thanks!

[Rover_KE]

will have

[Piscean]

Will here expresses certainty, not futurity.