docs: add related projects from the Elixir community (#7494)
docs: add related projects from the Elixir community (#7494)

Extend the ecosystem page with the following:i

- VegaLite (bindings for the Elixir programming language)
- Livebook (interactive and collaborative notebooks that supports VegaLite visualisations)
vega/vega-lite,uwdata/vega-lite,uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite