Update build docs (PaddlePaddle#148)

* Add automatic check AVX in CMake

* Add indent in FindAVX.cmake

* Revise table format and some words in build docs

* Update build docs

Refine ubuntu chinese doc

ISSUE=4610465


git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1464 1ad973e4-5ce8-4261-8a94-b56d1f490c56