Add check-in slot to summit calendar (#394)

Author: stefanv

content/summits/developer/2023/_index.md

@@ -44,7 +44,8 @@ during our event._
 | 9:00--9:30 | Welcome & coordination |
 | 9:30--13:00 | Work session |
 | 13:00--14:30 | Lunch & campus walk |
-| 14:30--18:00 | Work session |
+| 14:30--17:00 | Work session |
+| 17:00--18:00 | Check-in |
 | 19:00 | Dinner at [Eureka!](https://goo.gl/maps/g45EmtFn6bjUJSoS6) |
 {{< /details >}}
 
@@ -54,7 +55,8 @@ during our event._
 | 9:00 | Breakfast |
 | 9:30--13:00 | Work session |
 | 13:00--14:30 | Lunch & campus walk |
-| 14:30--17:45 | Work session |
+| 14:30--17:00 | Work session |
+| 17:00--17:45 | Check-in |
 | 18:30 | Dinner at [Kate's Pub](https://goo.gl/maps/HBFdQSzNkfKY427W9) |
 {{< /details >}}
 
@@ -64,7 +66,8 @@ during our event._
 | 9:00 | Breakfast |
 | 9:30--13:00 | Work session |
 | 13:00--14:30 | Lunch & campus walk |
-| 14:30-- | Work session |
+| 14:30--17:00 | Work session |
+| 17:00--18:00 | Check-in |
 | | Dinner (self organized) |
 {{< /details >}}
 
@@ -74,7 +77,8 @@ during our event._
 | 9:00 | Breakfast |
 | 9:30--13:00 | Work session |
 | 13:00--14:30 | Lunch & campus walk |
-| 14:30--18:00 | Work session |
+| 14:30--17:00 | Work session |
+| 17:00--18:00 | Check-in |
 | 19:00 | Dinner at [Big Time Brewery & Alehouse](https://goo.gl/maps/E55tA1vifpX9CeC76) |
 {{< /details >}}