configure github site maven plugin

[rremer]

The readme for https://github.com/mathieucarbou/license-maven-plugin is getting a little unwieldy, and was about to add to its length. We discussed briefly having these as normal maven sites (for plugins it's handy because you get the maven-plugin-plugin generated parameter documentation from the javadocs above the Parameters).

Here's an example of what this looks like: https://rremer.github.io/parent-pom/scm.html

I obviously deployed with alternate parameters so I could show it off, this was my deploy command:

mvn -Dparameter.site.subdomain=rremer -Dparameter.site.root.uri=parent-pom site site-deploy --settings /tmp/settings.xml

The important bit here is that downstream projects should have to configure anything at all, so if we want to update the parent (post release) in license-maven-plugin, you just do a mvn site site-deploy.

[mathieucarbou]

Thanks @rremer !
There is a license header missing in the XML file.

BTW, the projects are already published: https://mycila.carbou.me/

I have discovered yesterday thanks to your PR that my Cloudflare config was wrong and they went down.

Here is for MLP: https://mycila.carbou.me/license-maven-plugin/
And there is a link to the published site: https://mycila.carbou.me/license-maven-plugin/reports/4.0.rc1/license-maven-plugin/plugin-info.html

I am generating the sites and publish them on major releases to get the plugin info, so the README only serves as examples or doc that is more difficult to add as javadoc inside the plugin.