Unify docs for each software

[ES-Alexander]

I think the installation docs should instead be part of their respective main pages, and the Summary page can just link straight to that heading within the main page. At the moment our main pages for each software don't specify how to install, which is awkward from a UX perspective.

[ES-Alexander]

We currently have docs for each software in multiple places. It would be good to unify them into a single set of source files for each software, to reduce duplication and make versioning feasible. That should also help to make them easier to navigate, since the main source can be linked to from any summarisation pages instead of having some content that's hard to find depending on which page you're currently on.