Squeeze into the schedule the Zuul talk

The Zuul talk at the Gerrit User Summit Europe was really
interesting. With the forthcoming work by James on building
Gerrit on it, it becomes even more relevant for the Gerrit Community.

Replay the European talk and give an update on where we are
with the adoption in the Gerrit project.

Change-Id: I9e84efe752a1a090df628ed0a61f760b146b4747

schedule-usa.md

diff --git a/schedule-usa.md b/schedule-usa.md
index 785a8b2..15044f7 100644
--- a/schedule-usa.md
+++ b/schedule-usa.md
@@ -27,8 +27,9 @@
 | 11:45 | [Gerrit goes multi-site](sessions/gerrit-multi-site.md)                                      |
 | 12:45 | Lunch & Networking                                                                           |
 | 14:00 | [JGit (concrete topic to be decided)](sessions/jgit.md)
-| 15:00 | [Gerrit upgrades, step-by-step](sessions/gerrit-upgrades-step-by-step.md)                    |
-| 16:00 | Break & Networking                                                                           |
+| 14:45 | [Gerrit upgrades, step-by-step](sessions/gerrit-upgrades-step-by-step.md)                    |
+| 15:30 | [Using Zuul CI for the Gerrit Code Review project](sessions/zuul.md)                         |
+| 16:15 | Break & Networking                                                                           |
 | 16:30 | Lightning talks <br/>- [Show me your dashboard - 10'](lightning-talks/show-me-your-dashboards.md)
 | 17:30 | End of Day 1                                                                                 |
 | 19:00 | Dinner - Celebrations for Gerrit v3.0                                                        |