dev-release.txt: Verify the war version

...which I did not do for 2.15-rc0, so I invariably did it wrong.

Change-Id: I908d1b5445792eb5b311123f792e2539c87737c5

Documentation/dev-release.txt

diff --git a/Documentation/dev-release.txt b/Documentation/dev-release.txt
index 730b9e0..ddf7e7f 100644
--- a/Documentation/dev-release.txt
+++ b/Documentation/dev-release.txt
@@ -111,8 +111,12 @@
   ./tools/maven/api.sh install
 ----
 
-* Sanity check WAR
-* Test the new Gerrit version
+* Verify the WAR version:
++
+----
+  java -jar ~/dl/gerrit-$version.war --version
+----
+* Try upgrading a test site and launching the daemon
 
 * Verify plugin versions
 +