update site publish instructions

Any23 started to use maven-scm-publish-plugin in its early infancy (like 1.0-beta-1) ANY23-139

reading the deploy-site.sh script that was not updated for 9 years, I see that there are little changes that could be done to adapt to scm-publish 3.1.0 currently used

• not complex change from Any23 perspective, but the plugin would work better than curently
• from Maven's plugin perspective, this would solve some issues I saw when looking at MSCMPUB-48 that made me see that the plugin was not used the right way (now I see that it's because it is used the 1.0-bata-1 way, 9 years ago...)

I can propose PRs, I just need some feedback from Any23 team