Join multiple positions with a comma

Thank you so much for writing this blog post! I have one suggestion.

build_tsvector(["売り掛け金","売掛金"]) previously returned "売り:1 り掛:2 掛け:3 け金:4 金:59 売掛:7 掛金:8", but the documentation suggests that 金:59 should maybe be 金:5,9?

Again, THANK YOU for writing this blog post. I learned a lot of both technical Japanese and about full-text search!