Web [Charts]: Update readme for charts package

Created by: vovakulikov

Background

It's been a while since the last time when we updated our chart readme documentation, since then some chart API has been deprecated, some parts has been outdated.

In this issue we should update this doc, provide good examples and guidenes for any consumers that want to build their custom charts with our low level abstractions or just use our pre build in house components (that we primary use in Code Insights UI)