Update README * Align API Documentation with source code.  * Add missing methods `size` and `link` * Remove inapplicable references to accessor functions * Provide information about `nodes` and `links` * Clarify how links can be initialized based on numeric index into `nodes` array.
Update README
* Align API Documentation with source code.
 * Add missing methods `size` and `link`
* Remove inapplicable references to accessor functions
* Provide information about `nodes` and `links`
* Clarify how links can be initialized based on numeric index into `nodes` array.

d3/d3-sankey