Is it planned to be able to add additional documents to the experience section?
For example, if I wanted to add a letter of reference from my previous employer or a detailed overview of tasks and responsibilities.
A "Detailed Overview of Tasks and Responsibilities" -- that's what your CV is for. See mine for an example.
As far as "Letters of Reference"; they're something you can send to the company with a cover letter and a resume; but if you want them publicly available I'd link to them from your blog and include the link in the CV.
For example, maybe a sentence like the following in your Personal Statement or 'Background':