Make clear _global_changes DB is optional
diff --git a/src/install/setup.rst b/src/install/setup.rst
index 3443612..1b695c6 100644
--- a/src/install/setup.rst
+++ b/src/install/setup.rst
@@ -53,6 +53,11 @@
curl -X PUT http://127.0.0.1:5984/_global_changes
+Note that the last of these is not necessary if you do not expect to be
+using the global changes feed. Feel free to delete this database if you
+have created it, it has grown in size, and you do not need the function
+(and do not wish to waste system resources on compacting it regularly.)
+
See the next section for the cluster setup instructions.
.. _install/setup/cluster:
