Add link to Wikipedia article about MAC addresses

Author: scravy

README.md

@@ -3,7 +3,7 @@ node-macaddress
 
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-Retrieve MAC addresses in Linux, OS X, and Windows.
+Retrieve [MAC addresses](https://en.wikipedia.org/wiki/MAC_address) in Linux, OS X, and Windows.
 
 A common misconception about MAC addresses is that every *host* had *one* MAC address,
 while a host may have *multiple* MAC addresses – since *every network interface* may