fix(Dashboards): calling out broken billboard chart issue

src/content/docs/query-your-data/explore-query-data/dashboards/dashboards-charts-import-export-data.mdx

@@ -54,7 +54,7 @@ Keep in mind the following when you export a dashboard as PDF:
 
 * [Custom visualizations](/docs/query-your-data/explore-query-data/dashboards/add-custom-visualizations-your-dashboards/) aren't supported.
 
-* [Billboard charts](/docs/query-your-data/explore-query-data/use-charts/chart-types/#widget-billboard) that use the [`COMPARE WITH`](/docs/nrql/nrql-syntax-clauses-functions/#sel-compare) clause won't show percentages.
+* [Billboard charts](/docs/query-your-data/explore-query-data/use-charts/chart-types/#widget-billboard) that use the [`COMPARE WITH`](/docs/nrql/nrql-syntax-clauses-functions/#sel-compare) clause won't show percentages or render correctly with public chart links and exported images or PDFs.
 
 * Markdown widgets with large images may not display correctly or may not be fully visible.
 

src/content/docs/query-your-data/explore-query-data/use-charts/chart-types.mdx

@@ -125,6 +125,10 @@ A billboard chart is useful for single-stat queries like the [Apdex](/docs/apm/n
 
 You can also use billboards to compare a single value across states. For instance, use the [`COMPARE WITH`](/docs/insights/nrql-new-relic-query-language/nrql-reference/nrql-syntax-components-functions#sel-compare) clause to compare the same attribute across two different time frames.
 
+<Callout variant="important">
+Billboard charts that use the `COMPARE WITH` clause won't show percentages or render correctly with public chart links and exported images or PDFs.
+</Callout>
+
 To enable the data for a billboard chart, search for a single value. You can view multiple values by adding a facet from the dropdown.
 
 <DNT>