Update README.md
Merge pull request #188 from manuzhang/update_readme_doc

Update README.md
add fsio README
Merge pull request #192 from huafengw/seqio

add fsio README
update README
Merge pull request #193 from huafengw/updateREADME

update README
update readme
add dag and shuffle diagrams
Merge pull request #194 from manuzhang/update_doc

update readme
fix warning
Merge pull request #195 from manuzhang/fix_warning

fix warning