Update Gerrit v3.8.0 release plan

The Gerrit v3.8.0 release has been delayed because of two P0s raised:
- Issue 16894
- Issue 16942

New target for releasing is Friday 19th of May.

Change-Id: I2d27cdca31e8696518819b5e116c458a2b20693e
diff --git a/_posts/2023-03-31-gerrit-3.8-release-plan.md b/_posts/2023-03-31-gerrit-3.8-release-plan.md
index 95e9f66..b15c3a5 100644
--- a/_posts/2023-03-31-gerrit-3.8-release-plan.md
+++ b/_posts/2023-03-31-gerrit-3.8-release-plan.md
@@ -19,12 +19,12 @@
 | Apr 24    | Release `3.8.0-rc3` - Feature freeze deadline      |
 | May  2    | Release `3.8.0-rc4`                                |
 | May  9    | Release `3.8.0-rc5`                                |
-| May  9-15 | Gerrit Hackathon in **TBC**                        |
-| May  15   | Final release of `3.8.0`                           |
+| May  9-15 | Gerrit Hackathon on Discord                        |
+| May  19   | Final release of `3.8.0`                           |
 
 ## Gerrit Hackathon
 
-The Gerrit hackathon is planned during the release week, fully remote and hosted on [Discord](https://discord.gg/M2p2gY2f?event=1103076281366622210).
+The Gerrit hackathon is planned during the release week, fully remote and hosted on Discord.
 
 We also encourage all the [JGit contributors and committers](https://projects.eclipse.org/projects/technology.jgit/who)
 to join the event.