Remove txt documents because KGTP has pdf version documents now.
* Update doc "Get help or report issues".
  https://code.google.com/p/kgtp/wiki/HOWTO#Get_help_or_report_issues
  https://code.google.com/p/kgtp/wiki/HOWTOCN#需要帮助或者汇报问题

* Update doc "Get KGTP through git".
  https://code.google.com/p/kgtp/wiki/HOWTO#Get_KGTP_through_git
  https://code.google.com/p/kgtp/wiki/HOWTOCN#通过git下载KGTP

* Update doc "Get KGTP through http".
  https://code.google.com/p/kgtp/wiki/HOWTO#Get_KGTP_through_http
  https://code.google.com/p/kgtp/wiki/HOWTOCN#通过http下载KGTP