add documentation for elevation api

docs/config.rst

@@ -258,6 +258,10 @@ For example::
     "source1": {
       "url": "mbtiles://source1.mbtiles",
       "type": "vector"
+    },
+    "terrain": {
+      "url": "mbtiles://terrain.mbtiles",
+      "encoding": "mapbox"
     }
   }
 
@@ -265,6 +269,8 @@ Alternatively, you can use ``mbtiles://{source1}`` to reference existing data ob
 In this case, the server will look into the ``config.json`` to determine what file to use by data id.
 For the config above, this is equivalent to ``mbtiles://source1.mbtiles``.
 
+If you use terrain tiles, it is possible to configure an ``encoding`` with ``mapbox`` or ``terrarium`` to enable a terrain preview mode and the ``elevation`` api for the ``data`` endpoint.
+
 PMTiles
 -------
 

docs/endpoints.rst

@@ -100,6 +100,14 @@ Source data
 
   * TileJSON at ``/data/{id}.json``
 
+  * If terrain mbtile data is served and ``encoding`` is configured (see config) the elevation can be queried 
+
+    * by ``/data/{id}/elevation/{z}/{x}/{y}`` for the tile
+
+    * or ``/data/{id}/elevation/{z}/{long}/{lat}`` for the coordinate
+
+    * the result will be a json object like ``{"z":7,"x":68,"y":45,"red":134,"green":66,"blue":0,"latitude":11.84069,"longitude":46.04798,"elevation":1602}``
+
 Static files
 ===========
 * Static files are served at ``/files/{filename}``