[v11.4.x] Docs: Add G12 release date to upgrade guide (#98748)

Co-authored-by: Isabel Matwawana <isabel.matwawana@grafana.com>
Co-authored-by: margotphelps <123196595+margotphelps@users.noreply.github.com>

docs/sources/upgrade-guide/when-to-upgrade/index.md

@@ -50,7 +50,7 @@ Currently, Grafana is on a monthly release cycle. Here’s a look at scheduled r
 | Feb. 18, 2025                | Supported versions                | Patching         |
 | March 25, 2025               | 11.6 & Supported versions         | Minor & patching |
 | April 15, 2025               | Supported versions                | Patching         |
-| May 2025                     | Grafana 12.0 & Supported versions | Major & patching |
+| May 5, 2025                  | Grafana 12.0 & Supported versions | Major & patching |
 
 ### A few important notes