Adds a lot of new information to the docs that will help developers better utilize the entire Chart.js library
List of implemented changes:
- Reverse option for legends (resolves#3102)
- Information about chart resizing (resolves#3023)
- Mixed chart types (resolves#2825) (resolves#2431)
- Chart library comparison table (resolves#2605)
- getDetasetMeta function information (resolves#2521)
- Popular Extensions (resolves#2365)
Add `beforeDatasetsUpdate` and `afterDatasetsUpdate` plugin notifications during the chart update. Plugins are able to cancel the datasets update by explicitly returning false to `beforeDatasetsUpdate`. For consistency, rename `(before|after)DatasetDraw` to `(before|after)DatasetsDraw`.