Redirect two NAR plugin links to the nar-maven-plugin website

The NAR plugin is an incredibly useful Maven plugin, so useful that a bunch of developers wanted to say thanks by offering to continue the development. This indeed happened, and there is an official website of the effort: https://maven-nar.github.io/.

Google searches for the NAR plugin easily lead to the website backed by this repository, so let's make it easier for users to find the NAR plugin website by linking to it in a more obvious manner.