Contribute back our version of the flag of Luxembourg

[Wyatt OʼDay]

See commit 833df0d

Fix flag of Luxembourg to use the correct colors as specified by their legislation:

http://data.legilux.public.lu/eli/etat/leg/memorial/1993/73/fr/pdf

Namely,

PANTONE Red 032 C, https://www.pantone.com/color-finder/Red-032-C
Hex: #EF3340

PANTONE 299 C, https://www.pantone.com/color-finder/299-C
Hex: #00A3E0

These changes should be contributed back here: https://commons.wikimedia.org/wiki/File:Flag_of_Luxembourg.svg