Update README.md

add design document for build_errors database
Update README.md

correct build error design document
git pull
Merge branch 'master' of github.com:monaca/medic

* 'master' of github.com:monaca/medic:
  Update README.md
  Update README.md
support for pulling tags
Merge branch 'master' of git://github.com/filmaj/medic

* 'master' of git://github.com/filmaj/medic:
  support for pulling tags
merge filmaj master