Create chart documentation

For somebody new to the chart module, it appears to be quite a challenge to figure out where to get started, especially because documentation is spread over various places (outside of Drupal.org), or is simply missing.
Here are some more details about this:

1. The chart module is NOT included in the list of Contributed modules documentation. Refer to #2370851: Create community docu for chart for progress on this item.
2. Moreover, the Read documentation link on the chart project page doesn't link to anywhere within drupal.org, which implies that drupal.org authorizations aren't sufficient for anybody interested in contributing to the community. Refer to #2370851: Create community docu for chart for progress on this item.
3. On top of that, there are 19 documentation issues in a status different from closed (fixed), about 33% of them are still in status active.

As a followup of the #2368793: Chart 2.0 'initiative' (is it OK to use that term, or anybody who has a better one?), I suggest to use this issue to address the above challenge, and also use it as a parent issue for the various existing documentation issues, as well as potentially additional (new) documentation issues being filed.

Unless I hear anything different from any of the existing chart maintainers, I'll assume they're OK with this approach. Having good documentation about what the current chart module has to offer, seems to me like a prerequisite to start addressing migrating and / or upgrading the chart module in the near future. For anybody interested in getting an idea of the kind of documentation I would like to achieve, checkout the available community documentation about forena reports, which I recently created more or less from scratch (as a new co-maintainer of the forena module also).

To be complete: any type of help / contributions from any of the existing +25K sites to address this challenge would be appreciated. Suggestions?