Update README.md

Author: jackparmer

README.md

@@ -4,7 +4,7 @@
 [![circle ci](https://circleci.com/gh/plotly/plotly.js.png?&style=shield&circle-token=1f42a03b242bd969756fc3e53ede204af9b507c0)](https://circleci.com/gh/plotly/plotly.js)
 
 #### 📢 Announcement!
-#### Spots are still available for a 2 day, Plotly.js master class in NYC, November 16-17. 
+#### Seats are still available for a 2 day, Plotly.js master class in NYC, November 16-17. 
 #### [Registration here](https://plotcon.plot.ly/workshops) 🎨 📈 🗽
 
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