Remove page “Your First Lines of Scala”

[julienrf]

Replace it with a redirection to https://docs.scala-lang.org/overviews/scala-book/hello-world-1.html

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I recently noticed that people searching for “scala hello world” on Google land to this “orphan” page: https://scala-lang.org/documentation/your-first-lines-of-scala.html

This page is not maintained, and the only link that points to it within https://scala-lang.org is at the bottom of another unmaintained page: https://www.scala-lang.org/download/install.html

This PR redirects https://scala-lang.org/documentation/your-first-lines-of-scala.html to https://docs.scala-lang.org/overviews/scala-book/hello-world-1.html, and updates https://www.scala-lang.org/download/install.html.

[adpi2]

LGTM!