Police report speed of accident

Got rear ended on the highway this morning. Got cut off, traffic bottleneck necked, sudden braking, nearly avoided hitting the car that cut me off, got rear ended while dramatically decreasing in speed to almost 0.

Police came, they asked me how fast I was going when the accident happened. I was pretty blurry at the moment and kinda confused because I was rapidly declining in speed when I got hit so I wasn’t sure. The cop said “so about 40” I said “I guess” so that’s what he wrote. In reality, I was damn near at a full stop. Should I call and tell them this ? I know regardless I’m not at fault, but I may have additional claims to file and I’m not sure if updating the speed of the accident will change things.