With the product and documentation in the hands of customers, you will continue to review and iterate to improve your content.
Be sure to provide users with a simple way to give feedback on what they're reading. A simple "Was This Helpful?" prompt on your documentation site or a web form people can visit from a documentation PDF provide great opportunities to capture user's thoughts in the wild. If possible, find a way to signal to users when their feedback is incorporated. Even a simple note in your product change log saying the improvement was submitted by a user shows you're listening.
Learn more about collecting user feedback.
The team supporting your product receives customer feedback all the time. Work to build relationships with the Support team, encourage them to write knowledge base articles, and provide them an easy way to give documentation feedback. Empowering Support with improved documentation is a great way to reduce Support burden for the product and having a rich knowledge base is a great way to identify new content that should be added in the future.
Time Tracking Analysis
As your team writes together, it's important to keep track of the time spent. Now, you might be thinking time tracking is only so leadership can micromanage your writing. Yuck; no. Time logs are actually a very important source of feedback for your team. You should track both the time each team member spends on their part of a documentation task and the total time spent on the task. The two values are helpful to the team because they illustrate parts of the process that take a long time, spurring on improvement and better ability to estimate work in the future.