RFR: 8302879: doc/building.md update link to jtreg builds

Mon Feb 20 16:37:25 UTC 2023

On Mon, 20 Feb 2023 14:22:40 GMT, George Adams <gdams at openjdk.org> wrote:

> The Eclipse Adoptium project recently moved its CI from ci.adoptopenjdk.net to ci.adoptium.net. The link to jtreg builds needs updating
> 
> See https://github.com/adoptium/infrastructure/issues/2932 for more context

Looks fine to me.

-------------

Marked as reviewed by sgehwolf (Reviewer).

PR: https://git.openjdk.org/jdk/pull/12665