Right now, the no longer maintained table suggests that the last release
for the 3.28 LTS was 3.28.11. This is incorrect, as 3.28.12 was released
in May of 2023. Let's update this table to reflect that.

Right now, the no longer maintained table suggests that the last release
for the 3.24 LTS was 3.24.6. This is incorrect, as 3.24.7 was released
in November of 2022. Let's update this table to reflect that.

Right now, the no longer maintained table suggests that the last release
for the 3.20 LTS was 3.20.3. This is incorrect, as 3.20.6 was released
in November of 2020. Let's update this table to reflect that.

It would be useful to show rough "Bugfix until" and "Security patches
until" dates for the no longer maintained LTS versions (similar to how
we do for the currently maintained LTS versions).

Let's make it so!

…until dates