Move dev guide to single page to make navigation easier

[PietrH]

Currently I find it unclear on how to get from page to page on the dev guide website.

For example, when navigating from the introduction page https://docs.b-cubed.eu/dev-guide/ to the page on repositories https://docs.b-cubed.eu/dev-guide/code-repositories/, or R: https://docs.b-cubed.eu/dev-guide/r/ it's not immidiatly clear to me that I'd have to navigate via the header menu

I believe it might be better put everything on a single page instead. Then we can:

• Use the navigation on the side get to major headers
• Use Ctrl + F for search

Example:

Already briefly discussed with Peter. What do you think?

[peterdesmet]

Note to self:

• [x] Bundle
• [x] Chapter authors
• [x] Headings
• [x] References
• [x] Internal links