Add beta access notice to Map chart documentation (#292)

* Update references/chart-types.mdx

Co-Authored-By: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>

* Update references/chart-types.mdx

Co-Authored-By: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>

---------

Co-authored-by: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>

Author: mintlify[bot]

references/chart-types.mdx

@@ -416,6 +416,10 @@ The color range will use a set of 5 colors mapped across the min and max colors
 
 ### Map (Beta)
 
+<Info>
+This feature is in beta. Reach out to the Lightdash team if you'd like to get access.
+</Info>
+
 Maps display geographic data on an interactive map. They support three visualization modes:
 
 **Map types:**
@@ -430,6 +434,14 @@ Maps are useful when:
 - Showing regional performance or metrics
 - Displaying location-based patterns
 
+#### Data requirements
+
+The type of geographic data you have determines which map visualization you can use:
+
+- **Latitude and longitude coordinates** - If your data includes lat/lon fields, you can create scatter maps, bubble maps, or heatmaps to plot individual points.
+- **Country codes or US state codes** - If your data contains standard geographic codes (like ISO country codes or US state abbreviations), you can create choropleth maps using the built-in region shapes.
+- **Custom geographic identifiers with GeoJSON** - If your data uses other geographic identifiers (like postal codes, sales territories, or custom regions), you can create choropleth maps by providing a custom GeoJSON file that defines the region boundaries.
+
 #### Layout options
 
 **Map type** - Choose between Scatter, Heatmap, or Area modes.