dates of fortnight-appearances

Hey,
I didn't found the request-tab in this repo, so I'll put this feature-request here.

It would be nice to have the last date(s) of a fortnights appearance written down somewhere.
I think, the best way to integrate this is in the drop-section above the two rows for difficulties and under the row with the condition.

Here's a (rough) example. "->" means it's in the second column, ` are table borders.

v Jailbreaking Baroque Works
`
Condition
-> Striker, Shooter and Slashers are weakend.
`
Appearances 
-> Japan: [whenever that was]
-> Global: Feb. 16 - Mar. 1 2016
`
[rows for Elite/Expert]
`

[optc-db]

I added the request Label for now, will have to think about adding the feature though
Not sure if that would crowd the table too much, especially with fortnights that have a challenge attached