e2e-tests: Document example test project existence

Change-Id: I6f3f01dc8c21e5eeef304ffa32f7556084cff2ca
diff --git a/Documentation/dev-e2e-tests.txt b/Documentation/dev-e2e-tests.txt
index 410dee0..8085866 100644
--- a/Documentation/dev-e2e-tests.txt
+++ b/Documentation/dev-e2e-tests.txt
@@ -95,6 +95,8 @@
 * `push`
 * `clone`
 
+The example above assumes that the `loadtest-repo` project exists in the Gerrit under test.
+
 == How to run tests
 
 Run all tests: