mongodb/docs — pull request #1901 by rueckstiess (2014-07-26 02:28:59+00:00)
Title: made the $unwind example more intuitive

having the same label twice ("fun") is possible, but not really intuitive, especially since we mention in the next sentence "each document is identical except for the value of the tags field".

also made a bit more realistic example matching the books/author theme.