Lead with platform support, then walk through the features with the
current screenshots and demo videos beside them. Each feature section
opens with the keys to press, keeps a short list visible, and moves
the long details into collapsed sections. The reference sections
fold their deep material the same way.
Remove the duplicated feature list from the roadmap and the repeated
help shortcuts. Split code blocks so each copy button copies one
runnable command or one sequence, and keep installer dry runs apart
from the install itself.
Mirror the new structure in the Simplified Chinese README.