docs: livebook and exdocs integrations (#2728)

* add LiveBook integration

* add link to mermaid graph integration into ex_doc

docs/integrations.md

@@ -20,6 +20,7 @@ They also serve as proof of concept, for the variety of things that can be built
   - [Mermaid Plugin](https://github.com/JozoVilcek/gitbook-plugin-mermaid)
   - [Markdown with Mermaid CLI](https://github.com/miao1007/gitbook-plugin-mermaid-cli)
   - [Mermaid plugin for GitBook](https://github.com/wwformat/gitbook-plugin-mermaid-pdf)
+- [LiveBook](https://livebook.dev) (**Native support**)
 - [Atlassian Products](https://www.atlassian.com)
   - [Mermaid Plugin for Confluence](https://marketplace.atlassian.com/apps/1214124/mermaid-plugin-for-confluence?hosting=server&tab=overview)
   - [CloudScript.io Addon](https://marketplace.atlassian.com/apps/1219878/cloudscript-io-mermaid-addon?hosting=cloud&tab=overview)
@@ -168,3 +169,5 @@ They also serve as proof of concept, for the variety of things that can be built
 - [Reveal CK](https://github.com/jedcn/reveal-ck)
   - [reveal-ck-mermaid-plugin](https://github.com/tmtm/reveal-ck-mermaid-plugin)
 - [mermaid-server: Generate diagrams using a HTTP request](https://github.com/TomWright/mermaid-server)
+- [ExDoc](https://github.com/elixir-lang/ex_doc)
+  - [Rendering Mermaid graphs](https://github.com/elixir-lang/ex_doc#rendering-mermaid-graphs)