Add Language Support for Luxembourgish

[tomh4]

It would be great if language support for Luxembourgish could be added (language code lb)
It is a fairly niche language, I am aware of that, thus I propose instead of writing a custom tokenizer, one could reuse the one for German and simply apply it to Luxembourgish, as both languages are fairly similar in regards to language & sentence structure and it would probably be enough, and better than not be able to use the language at all in meilisearch! :)

[curquiza]

cc @ManyTheFish for your information

[yapsr]

Would love to see a similar approach for supporting Dutch.