SI-7491 fix typo in scala.App documentation

[gourlaysama]

This is a really cheap PR, but hey, there was a ticket for it!

[som-snytt]

Since you have undertaken this onerous task, I would suggest stronger language.

For the normal use case, do not override `main`.  The whole class body becomes the "main method."

The other question is whether anyone who knows what they are doing would choose to override main.

[retronym]

How about:

trait App { 
 ....
  @deprecatedOverriding("main should not be overriden", "2.11.0")
  def main(args: Array[String]) = {

Then we can make if final in 2.12.

[som-snytt]

That's super. Preemptively, s/overriden/overridden/.

I'd forgotten about that deprecated mode. So basically, the upper limit on Scala features is what JZ can keep in his head. There must be a test for that; then, you can plan Scala 3 around the result.

[gourlaysama]

Good point, I don't think anyone ever chose to override main anyway. Here is the new version.

[retronym]

LGTM