fix typo in a comment

src/plot.js

@@ -711,7 +711,7 @@ function inheritScaleLabels(newScales, scales) {
 }
 
 // This differs from the other outerDimensions in that it accounts for rounding
-// and outer padding in the fact scales; we want the frame to align exactly with
+// and outer padding in the facet scales; we want the frame to align exactly with
 // the actual range, not the desired range.
 function actualDimensions({fx, fy}, dimensions) {
   const {marginTop, marginRight, marginBottom, marginLeft, width, height} = outerDimensions(dimensions);