Add links to previous versions of a notebook

[gaow]

The workflowr project recently added a new feature to show previous versions of a document. See here and below for example:

I think this is a really relevant feature. I can imaging my life becomes a lot easier with it. I'll do it in the summer for jnbinder (should be a day's work or less).

[BoPeng]

But this assume that the doc is saves to a git repository, right? This could potentially be done with a magic. I saw even something to show previous results, and that looks more difficult to me.

[gaow]

It would be great if some magic can take care of it. Yes this assumes a git repo, and possibly a github repo because the link to the older versions are github specific. In jnbinder I simply test if it is a git repo, and try to parse from the provided repo link in config file to provide proper support to github, bitbucket and gitlab.

I saw even something to show previous results, and that looks more difficult to me.

I think that feature is a bit of an over-engineering and a distraction. I'd keep each notebook focused on a specific topic, that usually has maybe less than 5 figures. Then showing all their versions is enough to me because one can just click over to that archived page and read it all.