Update the dev.bukkit.org Files page as part of the release process

[gerzytet]

Even though we advertise the github releases more, There are still a lot of people who download TriggerReactor through dev.bukkit.org.

I don't have good data for 3.0.x, but for release 2.2.1, there were 554 downloads from github and 464 downloads through bukkit. This is unsuprising since the dev.bukkit.org site is the first search result for "TriggerReactor" on google. All of our new releases should be there too. The last time it was updated was for 3.0.0 in December 2019