Remove circular definitions in documentation

[Mike Chabot]

These types of circular definitions aren't helping anyone. At the very least, the documentation should detail the arguments available in the callback, namely: event and index:

https://facebook.github.io/fixed-data-table/api-table-v0.5.html

onRowClick

Callback that is called when a row is clicked.

type: func

[Mike Chabot]

Linking #392
SO article: http://stackoverflow.com/questions/39150974/fixed-data-tables-function-onrowclick-not-returning-row-data