I checked "to doctor" in Longman Dictionary and it means:
to dishonestly change something in order to gain an advantage.
to add something harmful to food or drink
to remove part of the sex organs of an animal to
to give someone medical treatment, especially when you are not a doctor.
I think the first meaning fits with the phrase but I am not sure.
Could you please tell me what the meaning of:
"He doctored the books"
The full text:
Shawn drove for days with little sleep, navigating our fifty-foot trailer as if it were his own arm. He doctored the books whenever we crossed a checkpoint, to make it seem he was getting more sleep than he was. Every other day we stopped to shower and eat a meal that wasn’t dried fruit and granola.