Updated Release schedule (markdown)

Release-schedule.md

@@ -18,6 +18,8 @@ Here are planned future releases and currently-supported Wagtail versions.
 
 ## Past versions
 
+All of Wagtail’s releases to date, in support and out of support.
+
 | Version        | Release date           | Active support      | Security support    |
 | -------------- |-----------------------:| -------------------:| -------------------:|
 | 6.1            | 1 May 2024             | 1 August 2024       | 1 November 2024     |