Update README

Author: mbostock

README.md

@@ -724,10 +724,8 @@ Insets are specified in pixels. Corner radii are specified in either pixels or p
 Given a *mark*, such as the result of calling [Plot.barY](#plotbarydata-options), you can call *mark*.plot to render a plot. This is [shorthand](https://observablehq.com/@observablehq/plot-shorthand?collection=@observablehq/plot) for calling [Plot.plot](#plotplotoptions) where the *marks* option specifies this single mark.
 
 ```js
-{
-  const mark = Plot.barY(alphabet, {x: "letter", y: "frequency"});
-  return mark.plot();
-}
+const mark = Plot.barY(alphabet, {x: "letter", y: "frequency"});
+return mark.plot();
 ```
 
 More commonly this shorthand is written as a single expression: