Change Senlin meeting to different biweekly times

As discussed in the last Senlin meeting [1] and on the mailing list [2]
[3], we agreed to have different meeting times for even and odd weeks to
allow developers in different timezones to attend.

[1] http://eavesdrop.openstack.org/meetings/senlin/2018/senlin.2018-11-30-05.30.log.html#l-44

[2] http://lists.openstack.org/pipermail/openstack-discuss/2018-November/000421.html

[3] http://lists.openstack.org/pipermail/openstack-discuss/2018-December/000469.html

Change-Id: I2e0a4610a1f40499cf9fcad2cb9a8e5eea585d39

meetings/senlin-team-meeting.yaml

@@ -5,8 +5,13 @@ schedule:
   - time:       '0530'
     day:        Friday
     irc:        senlin
-    frequency:  weekly
-    start_date: 20180824
+    frequency:  biweekly-even
+    start_date: 20181214
+  - time:       '1900'
+    day:        Thursday
+    irc:        senlin
+    frequency:  biweekly-odd
+    start_date: 20181206
 chair: Duc Truong (dtruong)
 description:  >
   The Senlin project team holds a weekly team meeting.