Add shiny express example

docs/examples/getting_started/shiny_express.py

@@ -0,0 +1,28 @@
+import json
+
+from shiny.express import input, render, ui
+
+from maplibre import Map, MapOptions, render_maplibregl
+
+ui.h1("My awesome MapLibre map")
+
+
+@render_maplibregl
+def mapgl():
+    return Map(MapOptions(zoom=3, pitch=40))
+
+
+ui.div("Click on map to show coords.")
+
+
+@render.code
+def coords():
+    return str(input.mapgl_clicked())
+
+
+ui.div("Move map to change view state.")
+
+
+@render.code
+def views_tate():
+    return json.dumps(input.mapgl_view_state(), indent=2)