You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "when did nhl start 3 on 3 overtime?" whose answer is 2015–16 NHL season.
Each document should contain about 30 words, and these documents should contain useful information.

Query: NHL 3 on 3 overtime start year
Useful Output:

Doc 1: For years, there were four skaters on each side, but the NHL adopted the three-on-three format at the start of the 2015-16 season. If a
Doc 2: After watching, tracking and studying 243 overtime periods during the 2019-20 season, here are the keys to 3-on-3 overtime success.
Doc 3: Beginning with the 2020-21 season, college hockey games tied after regulation will go to a five-minute 3-on-3 overtime period.
Doc 4: Trading breakaways and playing at a frenetic pace was what 3-on-3 was about when it debuted in 2015. The idea was to open up the ice for skilled
Doc 5: During the regular season, the NHL's overtime period lasts five minutes and is played in a 3-on-3 format (excluding goaltenders). Why fewer