Update layers.md (#2118)

Fix type from #2117 (comment).

Author: nvkelso

docs/layers.md

@@ -2,7 +2,7 @@
 
 ![image](images/mapzen-vector-tile-docs-all-layers.png)
 
-The [Tilezen vector tiles](https://mapzen.com/projects/vector-tiles) provides worldwide basemap coverage sourced from [OpenStreetMap](http://www.openstreetmap.www.openstreetmap.org) and other open data projects, updated intermittently as a free & shared service at [Nextzen.org](http://www.nextzen.org).
+The [Tilezen vector tiles](https://mapzen.com/projects/vector-tiles) provides worldwide basemap coverage sourced from [OpenStreetMap](http://www.openstreetmap.org) and other open data projects, updated intermittently as a free & shared service at [Nextzen.org](http://www.nextzen.org).
 
 Data is organized into several thematic layers, each of which is named, for example; `buildings`, `pois`, and `water`. A selection of these layers are typically used for base map rendering, and are provided under the short-hand name `all`. Each layer includes a simplified view of OpenStreetMap data for easier consumption, with common tags often condensed into a single `kind` field as noted below.