readme: we don't support windows or macos
Fixed typos
readme: tell people to use alpha-r2748 instead of release-1.5.27.1-beta
Add lazyload images with beacon test.
Revert "Add lazyload images with beacon test."

This reverts commit d5ea62cdfcb4b9a438f358436c6d034e2d9b6e4f.