Wiki per-month era tags

[Dolalin]

With songs and spells and items now being gated by month, we could use per-month "Era" tags to let players know which month to expect a spell/item/song to unlock in.

Anyone more wiki familiar want to set some up and we can start tagging stuff?

"Launch"
"April 1999"
"May 1999"
"June 1999"
...
Etc. Right up to Dec 2001.