[N1QL Tutorial] Good to update the tutorial with latest N1QL features

Hi Query Team,

The http://query.pub.couchbase.com/tutorial/#index is super useful for customers to play with N1QL. Noticed some recent very useful N1QL additions are not yet reflected on the tutorial.

It would be great if we can add more latest feature examples on the tutorial as well.
Example:
1. Array Indexing
2. Prepared Statements **
3. Index-Join
4. Union, Union All
5. Covering Indexes w/ Explain ( maybe)
6. some additional commonly used functions - like date conversions