Make Docker information more notable in INSTALL.md

INSTALL.md

@@ -1,5 +1,7 @@
 # Installation
 
+This document describes how to manually configure your system for running openstreetmap-carto. If you prefer quick, platform independent setup for a development environment, without the need to install and configure tools by hand, follow a Docker installation guide in [DOCKER.md](https://github.com/gravitystorm/openstreetmap-carto/blob/master/DOCKER.md).
+
 ## OpenStreetMap data
 You need OpenStreetMap data loaded into a PostGIS database (see below for [dependencies](#dependencies)). These stylesheets expect a database generated with osm2pgsql using the pgsql backend (table names of `planet_osm_point`, etc), the default database name (`gis`), and the [lua transforms](https://github.com/openstreetmap/osm2pgsql/blob/master/docs/lua.md) documented in the instructions below.
 
@@ -104,8 +106,6 @@ For deployment, CartoCSS and Mapnik are required.
 
 Remember to run CartoCSS with proper API version to avoid errors (at least 3.0.0: `carto -a "3.0.0"`).
 
-We offer Docker containers for quick setup of your development environment. See [DOCKER.md](https://github.com/gravitystorm/openstreetmap-carto/blob/master/DOCKER.md) for details.
-
 ---
 
 For both development and deployment, a database and some utilities are required