Why not get it read by a couple peers and iterate on their feedback? My writing is not great, but with the design docs I created, the first version is always terrible, not easily understandable mostly because of not listing all the assumptions whereas the third version almost always becomes something I would never be able to achieve myself. Over the years, I settled on 2 rounds of review. First to mostly add missing sections and rearchitect the design and the doc, second to mostly hone the explanation/details.