Merge branch 'mg/maint-doc-sparse-checkout'

* mg/maint-doc-sparse-checkout:
git-read-tree.txt: correct sparse-checkout and skip-worktree description
git-read-tree.txt: language and typography fixes
unpack-trees: print "Aborting" to stderr

diff --cc Documentation/git-read-tree.txt
Simple merge

diff --cc unpack-trees.c
Simple merge