This adds a minimal Arabic stemmer based on https://github.com/MihaiValentin/lunr-languages/blob/master/lunr.ar.js

[whb611]

This adds a minimal Arabic stemmer based on https://github.com/MihaiValentin/lunr-languages/blob/master/lunr.ar.js

I originally wrote this for use with mdBook. It's not a full port of the JS implementation, as I found many things in the original code to make search quality worse for my use case. If there is a requirement to be fully compatible with lunr-languages, I think I can work on a full port sometime.

Originally posted by @abdnh in mattico/elasticlunr-rs#40