[sf-lug] check release signatures

[Rick Moen]

Quoting aaronco36 (aaronco36 at SDF.ORG):

> Could very well be just this user alone, but haven't yet myself
> figured out just _Why_, in the 'mv' statement of [5], that
> "original" .sha256 checksum file would somehow need to be completely
> renamed/converted all the way to an .iso.sig file?

I actually did explain why:  In my ISOs collection, I maintain a
consistent file-naming convention across the entire set of downloaded 
files, which at their various places of origin don't follow _any_ 
specific file-naming convention.

It wasn't _necessary_ to impose order out of chaos.  I just chose
to do so, to make things consistent and easily understandable 
within the collection.

Sorry if the reason wan't clear, but I could swear I said why I 
chose to do that.