docs: add api docs, plus ensure voronoi img in mkdocs

Author: spwoodcock

docs/api.md

@@ -1,6 +1,29 @@
 # API Docs
 
-<!-- ::: pg_nearest_city.reverse_geocode.city_from_geopoint
+## Async Reverse Geocode
+
+::: pg_nearest_city.AsyncNearestCity
+options:
+show_source: false
+heading_level: 3
+
+## Sync Reverse Geocode
+
+::: pg_nearest_city.NearestCity
+options:
+show_source: false
+heading_level: 3
+
+## Query Output
+
+::: pg_nearest_city.Location
+options:
+show_source: false
+heading_level: 3
+
+## Database Configuration
+
+::: pg_nearest_city.DbConfig
 options:
 show_source: false
-heading_level: 3 -->
+heading_level: 3

docs/voronoi_italy.jpg

@@ -0,0 +1 @@
+../voronoi_italy.jpg