Modernize ActiveMQ Website

Create a new website with a more modern look and feel and also aligned with other Apache projects. At least initially, the content should remain the same. This is also an apportunity for fixing broken links thare still linger here and there.

I think we should keep it simple and continue some sort of static website generator.

Open questions:

1. Should we use https://infra.apache.org/asf-pelican.html or use some other platform (Hugo, Jekyll, etc...) and some JS/CSS framework (Tailwind, Bootstrap, etc...).

Start by reviewing the current ActiveMQ website and the ASF Pelican guidance linked in the issue, then compare Hugo and Jekyll with the proposed Tailwind or Bootstrap options. The work is done when the site has a modern Apache-aligned look, preserves the existing content, uses a chosen static-site approach, and fixes lingering broken links.

Written by the indexing model from the issue text.