Update document to reflect right versions, new features and big improvements on 2.8 release.
Update document to reflect right versions, new features and big improvements on 2.8 release.

(cherry picked from commit fbcc45c8d1f0c72fa72466515a7443075a28c71e)

zrccxyb62/hadoop,zrccxyb62/hadoop,zrccxyb62/hadoop,zrccxyb62/hadoop,zrccxyb62/hadoop,zrccxyb62/hadoop,zrccxyb62/hadoop