--- a/README	Wed Apr 08 21:59:47 2015 +0200
+++ b/README	Tue Apr 14 23:36:09 2015 +0200
@@ -20,6 +20,12 @@
 This command should create some docker images, called
 =eximtest/<platform>=.
 
+== Configure the test binary
+
+If you have a custom build config (EDITME), place it in
+exim/src/Local/Makefile, as usual. Otherwise we'll use a standard
+configuration.
+
 == Run the tests
 
     docker run -i -t -h foo.site eximtest/<platform>
@@ -38,4 +44,3 @@
     5601    debian7 opensuse
     0548    fedora21
 
-