description for scatterternary.fill, separate from scatter.fill

Author: alexcjohnson

src/traces/scatterternary/attributes.js

@@ -81,7 +81,18 @@ module.exports = {
     },
     connectgaps: scatterAttrs.connectgaps,
     fill: extendFlat({}, scatterAttrs.fill, {
-        values: ['none', 'toself', 'tonext']
+        values: ['none', 'toself', 'tonext'],
+        description: [
+            'Sets the area to fill with a solid color.',
+            'Use with `fillcolor` if not *none*.',
+            'scatterternary has a subset of the options available to scatter.',
+            '*toself* connects the endpoints of the trace (or each segment',
+            'of the trace if it has gaps) into a closed shape.',
+            '*tonext* fills the space between two traces if one completely',
+            'encloses the other (eg consecutive contour lines), and behaves like',
+            '*toself* if there is no trace before it. *tonext* should not be',
+            'used if one trace does not enclose the other.'
+        ].join(' ')
     }),
     fillcolor: scatterAttrs.fillcolor,
     marker: {