Fixed typo in docs/ref/contrib/gis/tutorial.txt.
@@ -746,7 +746,7 @@ position.
~~~~~~~~~~~~~~~
With the :class:`~django.contrib.gis.admin.OSMGeoAdmin`, GeoDjango uses
-a `Open Street Map`_ layer in the admin.
+an `OpenStreetMap`_ layer in the admin.
This provides more context (including street and thoroughfare details) than
available with the :class:`~django.contrib.gis.admin.GeoModelAdmin`
(which uses the `Vector Map Level 0`_ WMS dataset hosted at `OSGeo`_).
