Links in the search results for NixOS 20.09 started throwing 404
otherwise. Not all channels are being pushed to nixpkgs-channels as
apparently it is being phased out.
- still muse multi_match but now with cross_fields type
- add edge n-gram index field since cross_fields works only with match
and this way we can have prefix support
- suffix support is still supported as before by reversing the words in
data and query
- for query we now create variations of all multi_match queries. from 2
words you get 4 queries, from 3 works you get 8 queries and so on.
