Squashed 'sub/' content from commit 8a977ad

git-subtree-dir: sub
git-subtree-split: 8a977ada5c96b7f8d7ead115b081dd3d46d3a4f0
Merge commit '6c776a9af75629acee6698c6c967a80bb46c9ad0' as 'sub'
changed subtree readme