Britt Reid, the former Kansas City Chiefs assistant coach, pleaded guilty Monday to felony driving while intoxicated and causing a 2021 crash that severely injured a 5-year-old girl in another vehicle. During the 30-minute hearing, Reid admitted that on Feb. 4, 2021, he was intoxicated when his pickup truck slammed into two vehicles on the side of an entrance ramp along Interstate 435, near the team’s practice facility. The wreck injured two children, including Ariel Young, who suffered a traumatic brain injury. “I regret what I did. I made a huge mistake,” said Reid, 37. “I apologize to the f…