[EN] Support "mul-domino def" template

[BoboTiG]

• Wiktionary page: https://en.wiktionary.org/w/index.php?title=%F0%9F%80%B4
• Model link: https://en.wiktionary.org/wiki/Module:mul-domino_def

Words using this template are failing with a Lua error:

LUA error in #invoke('mul-domino def', 'definition') parent ('Template:mul-domino def', {}) at ['🀴', 'Template:mul-domino def', '#invoke', '#invoke']
[string "Module:string utilities"]:1328: bad argument #1 to 'gsub' (string expected, got nil)

Let's override it since it is a simple one.