docs: render the Source option labels in bold like the page's other controls

Author: igorlukanin

docs-mintlify/docs/explore-analyze/charts/chart-types/map.mdx

@@ -58,7 +58,7 @@ Clustering groups nearby points into a single circle that expands on zoom. It is
 
 A region map requires:
 
-- **Source** — the GeoJSON to render: `World Countries`, `US States`, or `Custom`.
+- **Source** — the GeoJSON to render: **World Countries**, **US States**, or **Custom**.
 - **Property** — which property in each GeoJSON feature acts as the join key (e.g. `name`, `ISO3166-1-Alpha-2`, `ISO3166-1-Alpha-3`, `state_code`).
 - **Dimension** — which column from your query joins to **Property**.
 - **Measure** — the numeric measure that drives the choropleth fill.