message: Add temporary docs link until site is live
diff: <!-- markdownlint-enable no-inline-html -->
  -[Demos][demo-url] | [Documentation](https://tradingview.github.io/lightweight-charts) | [Discord community](https://discord.gg/E6UthXZ)
  +[Demos][demo-url] | [Documentation](https://github.com/tradingview/lightweight-charts/tree/b58f2c3e7f539db5baab660bc50842367f5ed4fb/docs) | [Discord community](https://discord.gg/E6UthXZ)
  TradingView Lightweight Charts are one of the smallest and fastest financial HTML5 charts.
  