function_score: match only document with score above custom score thresh...

...old

functon_score matched each document regardless of the computed score.
This commit adds a query parameter `min_score` (-Float.MAX_VALUE default).
Documents that have a score lower than this threshold will not be mached.

closes #6952
typo with "documents", and "per default" doesn't really make sense.  Perhaps:

"By default, modifying the score does not change which documents match. To exclude..."