Update README.md

Author: mbostock

README.md

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 # d3-array
 
-Data in JavaScript is often represented by an iterable (such as an [array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array), [set](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Set) or [generator](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Generator)), and so iterable manipulation is a common task when analyzing or visualizing data. For example, you might take a contiguous slice (subset) of an array, filter an array using a predicate function, or map an array to a parallel set of values using a transform function. Before looking at the methods that d3-array provides, familiarize yourself with the powerful [array methods built-in to JavaScript](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array/).
+Data in JavaScript is often represented by an iterable (such as an [array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array), [set](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Set) or [generator](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Generator)), and so iterable manipulation is a common task when analyzing or visualizing data. For example, you might take a contiguous slice (subset) of an array, filter an array using a predicate function, or map an array to a parallel set of values using a transform function. Before looking at the methods that d3-array provides, familiarize yourself with the powerful [array methods built-in to JavaScript](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array).
 
 JavaScript includes **mutation methods** that modify the array: