Link to dev environment instructions from installation guide

docs/contributing.rst

@@ -7,6 +7,8 @@ Datasette is an open source project. We welcome contributions!
 
 This document describes how to contribute to Datasette core. You can also contribute to the wider Datasette ecosystem by creating new :ref:`plugins`.
 
+.. _devenvironment:
+
 Setting up a development environment
 ------------------------------------
 

docs/installation.rst

@@ -83,3 +83,5 @@ If you want to install Datasette in its own virtual environment, use this::
 You can now run Datasette like so::
 
     datasette fixtures.db
+
+If you want to start making contributions to the Datasette project by installing a copy that lets you directly modify the code, take a look at our guide to :ref:`devenvironment`.