Feature Request: Move wiki back into repo

[MichaelAkvo]

What are you trying to do?

Write documentation with references to code and issues.
The wiki doesn't allow referencing code documentation easily. One can only link to the latest code using an absolute URL (https://akvo.github.io/akvo-rsr/path/to/code).

Additionally, it's not possible to link to issues in the commits. It would be great to allow this when writing a new feature and the accompanying documentation for the feature.

Describe the solution you'd like

Move the documentation back into the repo, under the doc/ dir.
It would also allow us to get rid of the wiki altogether

Have you consider alternatives?

Not sure how else the problem could be solved.

Additional context

No response