Update README.md (#754)

Author: EE2dev

README.md

@@ -450,7 +450,7 @@ Plot.barY(alphabet, {x: "letter", y: "frequency", sort: {x: {value: "y", reverse
 
 If the input channel is *data*, then the reducer is passed groups of the mark’s data; this is typically used in conjunction with a custom reducer function, as when the built-in single-channel reducers are insufficient.
 
-Note: when a string or a function, the sort option is interpreted as a [basic sort transform](#transforms). To use both sort options and a sort transform, use [Plot.sort](#plotsortorder-options).
+Note: when the value of the sort option is a string or a function, it is interpreted as a [basic sort transform](#transforms). To use both sort options and a sort transform, use [Plot.sort](#plotsortorder-options).
 
 ### Facet options