Improved api docs (#128)

Author: kylebarron

docs/api/layers/path-layer.md

@@ -0,0 +1,11 @@
+# PathLayer
+
+The `PathLayer` renders lists of coordinate points as extruded polylines with mitering.
+
+![](../../assets/path-layer-roads.jpg)
+
+> Screenshot from North America roads example
+
+::: lonboard.PathLayer
+    options:
+      show_bases: false

docs/api/layers/scatterplot-layer.md

@@ -0,0 +1,11 @@
+# ScatterplotLayer
+
+The `ScatterplotLayer` renders circles at given coordinates.
+
+![](../../assets/scatterplot-layer-network-speeds.jpg)
+
+> Screenshot from Ookla example.
+
+::: lonboard.ScatterplotLayer
+    options:
+      show_bases: false

docs/api/layers/solid-polygon-layer.md

@@ -0,0 +1,19 @@
+# SolidPolygonLayer
+
+The `SolidPolygonLayer` renders filled and/or extruded polygons.
+
+```py
+import geopandas as gpd
+from lonboard import SolidPolygonLayer
+
+# A GeoDataFrame with Polygon geometries
+gdf = gpd.GeoDataFrame()
+layer = SolidPolygonLayer.from_geopandas(
+    gdf,
+    get_fill_color=[255, 0, 0],
+)
+```
+
+::: lonboard.SolidPolygonLayer
+    options:
+      show_bases: false

docs/api/traits.md

@@ -0,0 +1,5 @@
+# lonboard.traits
+
+::: lonboard.traits.ColorAccessor
+
+::: lonboard.traits.FloatAccessor

docs/api/top-level.md renamed to docs/api/viz.md

@@ -2,12 +2,8 @@
 
 The top-level namespace accessible after `import lonboard`.
 
+Layers are also accessible in the top-level namespace, but are documented in the `layers/` folder.
+
 ::: lonboard.viz.viz
     options:
       show_root_full_path: false
-
-::: lonboard.ScatterplotLayer
-
-::: lonboard.PathLayer
-
-::: lonboard.SolidPolygonLayer