Please update spec links and advisements to 2.13

[som-snytt]

The future is now.

[SethTisue]

three PRs and counting. wonder what else I'm missing.

• https://scala-lang.org/files/archive/spec/2.12/
• https://scala-lang.org/files/archive/spec/2.13/

[som-snytt]

Beautiful! Is it supposed to have a red banner announcing, THE FUTURE IS NOW?

Clicking around, I see the "Scala 2.13" button links to the change log, which says:

Trailing commas in expression, argument, type or pattern sequences are no longer supported.

It's just one of those things. Trailing commas are literally my favorite feature. Even after I recently discovered the sbt plugin that lets you omit all commas. Was it a big secret? Or maybe they decided it was too hard to explain trailing commas or no commas.

PS) not saying that change log is a must fix by any means. Just noting the irony. Because don't we subsist on irony? Anemia is just an irony deficiency.

[SethTisue]

"I am reasonably certain that a pull request removing the antiquated change log would be accepted,” he intoned a neutral voice, staring into the middle distance