Add an example of a pattern match on a sequence.

You can match against sequence types like List or Array just like
you match against case classes. Use the same syntax, but now you
can specify any number of elements within the pattern.

For example, this commit shows a pattern that checks for a
three-element list starting with zero.
Add an example of a sequence pattern with an unspecified number of pattern elements.

If you want to match against a sequence without specifying how long
it can be, you can specify _* as the last element of the pattern.

This funny-looking pattern matches any number of elements within a
sequence, including zero elements. Here is an example that matches
any list that starts with zero, regardless of how long the list is.