Add slide #18 of upstream training

Change-Id: I8ca41f67793ff0798ba62e0198c3aaf2d4c98182

doc/upstream-training/18-jenkins.rst

@@ -0,0 +1,41 @@
+Triggered on every commit
+=========================
+
+.. image:: ./_assets/18-01-triggered.png
+
+----
+
+Review in gerrit
+================
+
+.. image:: ./_assets/18-02-review.png
+
+----
+
+Error report
+============
+
+.. image:: ./_assets/18-03-error-report.png
+
+----
+
+False errors
+============
+
+.. image:: ./_assets/18-04-false-errors.png
+
+----
+
+Recheck bug #XXX
+================
+
+.. image:: ./_assets/18-05-recheck.png
+  :width: 85%
+
+----
+
+Exercise
+========
+
+add an error and match it to the jenkins message
+