Add configurable param example to README
@@ -134,6 +134,19 @@ name = "zoning" # used in the URL to reference this ma
provider_layer = "my_postgis.landuse" # must match a data provider layer
min_zoom = 10 # minimum zoom level to include this layer
max_zoom = 16 # maximum zoom level to include this layer
+
+ # configure addition URL parameters: /maps/:map_name/:layer_name/:z/:x/:y?param=value
+ # which will be passed to the database queries
+ [[maps.params]]
+ name = "param" # name used in the URL
+ token = "!PARAM!" # token to replace in providers.layers.sql query
+ type = "string" # one of: int, float, string, bool
+ sql = "AND param = ?" # SQL to replace the token in the query. ? will be replaced with a parameter value. If omitted, defaults to "?"
+ # if neither default_value nor default_sql is specified, the URL parameter is required to be present in all queries
+ # either
+ default_value = "value" # if parameter is not specified, this value will be passed to .sql parameter
+ # or
+ default_sql = " " # if parameter is not specified, this value will replace the .sql parameter. Useful for omitting query entirely
```
* More information on PostgreSQL SSL modes can be found [here](https://www.postgresql.org/docs/current/libpq-ssl.html).
