config_service: Fixed feedback button to autopopulate important fields
config_service: Fixed feedback button to autopopulate important fields

Changed the link in index.html to redirect users to the correct feedback
page.

BUG=747597

Review-Url: https://codereview.chromium.org/2984093002

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py