I have a bit of an unusual suggestion. One thig that had helped me is reading "The Economist". Their style is succinct, doesn't make lot of assumptions about reader's prior knowledge. Many a times I have read articles in it about many of the areas which I am barely familiar with and come out better informed. Probably that's what one would strive for in technical documentation.
Their style guide [1] is one of my references when trying to improve my own writing.
While my professional writing has been mostly academic, I find the progression is similar to tech writing.
First you learn to show your erudition and command of the ingroup speech.
Then, if you have a genuine desire to communicate, you progress to simpler yet precise language, stop using the big words when not necessary (often, they are just signaling and gatekeeping) and develop empathy for and understanding of the audience.
Definitely one of the best-written publications out there. Not as "literary" as The New Yorker. But brings in a certain amount of cleverness/humor/storytelling that newspapers (by design) mostly lack outside of feature stories where some of those elements can be overdone.
