[ticket/11220] Improvement to the info pop-up from "list="

A improvement to the info popup which is displayed when the cursor
is over the bbcode-button [list=] in the posting-editor

PHPBB3-11220
Merge remote-tracking branch 'Crizz0/ticket/11220' into develop-olympus

* Crizz0/ticket/11220:
  [ticket/11220] Improvement to the info pop-up from "list="