Initial documentation on using SpatiaLite

https://datasette.readthedocs.io/en/latest/spatialite.html

docs/index.rst

@@ -21,6 +21,7 @@ Contents
    sql_queries
    facets
    full_text_search
+   spatialite
    metadata
    config
    introspection

docs/spatialite.rst

@@ -0,0 +1,39 @@
+.. _spatialite:
+
+SpatiaLite
+==========
+
+The `SpatiaLite module <https://www.gaia-gis.it/fossil/libspatialite/index>`_ for SQLite adds features for handling geographic and spatial data. For an example of what you can do with it, see the tutorial `Building a location to time zone API with SpatiaLite, OpenStreetMap and Datasette <https://simonwillison.net/2017/Dec/12/location-time-zone-api/>`_.
+
+To use it with Datasette, you need to install the ``mod_spatialite`` dynamic library. This can then be loaded into Datasette using the ``--load-extension`` command-line option.
+
+Installing SpatiaLite on OS X
+-----------------------------
+
+The easiest way to install SpatiaLite on OS X is to use `Homebrew <https://brew.sh/>`_.
+
+::
+
+    brew update
+    brew install spatialite-tools
+
+This will install the ``spatialite`` command-line tool and the ``mod_spatialite`` dynamic library.
+
+You can now run Datasette like so::
+
+    datasette --load-extension=/usr/local/lib/mod_spatialite.dylib
+
+Installing SpatiaLite on Linux
+------------------------------
+
+SpatiaLite is packaged for most Linux distributions.
+
+::
+
+    apt install spatialite-bin libsqlite3-mod-spatialite
+
+Depending on your distribution, you should be able to run Datasette something like this::
+
+    datasette --load-extenison=/usr/lib/x86_64-linux-gnu/mod_spatialite.so
+
+If you are unsure of the location of the module, try running ``locate mod_spatialite`` and see what comes back.