relnote: Add a new feature entry for 14.12.

-  [WebUI] Support adding multiple servers by uploading tab-saparated-value file. (#789,#794)

Signed-off-by: YOSHIFUJI Hideaki <hideaki.yoshifuji@miraclelinux.com>
Merge branch '14.12_releng/releasenote' into 14.12_releng/master