add documentation for "data-bind" attribute syntax

[haberman]

I've found the Knockout documentation to be very good in general, but one thing I couldn't find explicit documentation about is the precise syntax of the data-bind attribute. Is it just JavaScript interpreted in the context of curly braces? Some examples show more complicated expressions, can this be arbitrary JavaScript? What if the arbitrary JavaScript contains a comma, is this handled?

A page documenting this syntax would be uber-helpful. Thanks for Knockout!

[mbest]

This documentation should also include information on ordering: that bindings for an element are evaluated left-to-right and that the order of bindings can be important when one depends on another.

It should also include information on dependencies between bindings for the same element and how to avoid such dependencies (hopefully simple once #321 is included).

[mbest]

done.