Add "updated on %date" text to each filter list

[Mikey1993]

Would be good to know when each of the lists was updated.
This will also help in some false positives situations as I had in #303.

[ialexsilva]

Add a tooltip: last update date: %date%

[Mikey1993]

Yeah, I agree that with the current UI, tooltip is a better approach IMHO.

[SW1FT]

This would be great, I've thought about this as well a while ago.

[gorhill]

For translators:

[alejandrolemus]

Why not add updated or last update: before those strings? Would be easier to know what it means, IMO.

[gorhill]

I want to be able to reuse these strings elsewhere too, which I won't be able if I make them specific. I am completely unsure whether Last update: {{ago}} works for all languages.

[alejandrolemus]

Maybe you could define Last update and {{x units ago}} as separate strings, and in this specific case build the tooltip from both? That way they are still independent and reusable (Last update seems like it could come handy in other situations, too).
Not that this is a really important issue, just trying to contribute with options here. Anyways, I would say that in Spanish Last update: {{ago}} would work just fine.

[Bushido1]

In Estonian [b]Last update: {{ago}}[/b] is good also and more understandable.

[gorhill]

Ok I will add a new string, Last update: {{ago}}, then translators can pick whatever is best, and if ever there is a language for which no meaningful translation can be found, then a translator can fall back on {{ago}}, which will give same result as it is now.