Clarify debugging of integration tests

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1577106 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/README.txt b/README.txt
index 16d4d10..c746d00 100644
--- a/README.txt
+++ b/README.txt
@@ -3,7 +3,6 @@
 This module builds a Sling instance using bundles from the trunk, and
 runs integration tests against it, via HTTP.
 
-
 Getting Started
 ===============
 
@@ -35,7 +34,9 @@
 To run individual tests, see the README.txt in that module.
 
 Use mvn launchpad:run to start this test instance, allows you to run
-and debug individual tests against it.
+and debug individual tests against it. The standard MAVEN_OPTS environment
+variable can be used to activate debugging of the Sling instance that's 
+being tested.
 
 Using Reactor Builds
 ----------------