Add PricePlow to README

README.md

@@ -58,6 +58,9 @@ Examples of Slate in the Wild
 * [Orchestrate.io API docs](https://docs.orchestrate.io/)
 * [ChaiOne Gameplan API docs](http://chaione.github.io/gameplanb2b/#introduction)
 * [Drcaban's Build a Quine tutorial](http://drcabana.github.io/build-a-quine/#introduction)
+* [PricePlow API docs](https://www.priceplow.com/api/documentation)
+
+(Feel free to add your site to this list in a pull request!)
 
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