The term “neurodiversity” (or ND for short) was first coined by the social scientist Judy Singer in the 1990s. It refers to a difference in brain processing that can affect social interaction, learning, attention, sensory processing, and other aspects of interacting with the world and other people. It has become a collective term for conditions such as autism, ADHD, dyslexia, dyscalculia, and dyspraxia.
Some estimates suggest 15% of adults are ND. That translates to one in seven employees. Potentially, a sizeable chunk of your workforce could be alienated by the presence of text-heavy documents and some individuals may be sufficiently impacted by their condition to be protected under the disability discrimination legislation which places a positive obligation on an employer to consider reasonable adjustments.
There could  be circumstances where a text-heavy document is justified, and staff handbooks and policies may be included in this. But sometimes employers may have a legal responsibility to consider alternatives, such as using flowcharts, graphics, or process maps? Regardless of legal obligation, they are likely to be more inclusive towards the 15% of your staff who may be ND.
In any situation, I would advise being sensitive to possible neurodiversity issues and where you are aware of then, involving employees to see what they would find beneficial.