Create HTML version of working group brief

We would like to create a page on eclipse.org/collaborations/working-groups/brief

The content can be found here: https://docs.google.com/document/d/1txr-cViq8ORKZmpXugQfRxxqJxOfEa3m/edit. Note that we are missing one quote in section 2, but that won't impact the layout.

@mkokabi will provide the design assets.

This is a Q4 MBO, but launching it in October or November would be preferred.