* clarify debug session launch sequence

Closes #497

As referenced in that issue, the flow diagram for starting a debug
session was not super clear and was very implicit about the constraints
previously discussed in microsoft/vscode#4902 (comment)

This attempts to refine that with a better diagram and textual description.

I also added a small script to build the diagrams, and to ensure they
displayed well I added a devcontainer setup and updated Jekyll as
necessary (the very old version we were on no longer built on modern
Ruby versions.)

* add ignore

* use mmd extension

* Support for ANSI styling in debug output and variables

Fixes #500

* fix typo

Bumps [webrick](https://github.com/ruby/webrick) from 1.8.1 to 1.8.2.
- [Release notes](https://github.com/ruby/webrick/releases)
- [Commits](ruby/webrick@v1.8.1...v1.8.2)

---
updated-dependencies:
- dependency-name: webrick
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Bumps [ws](https://github.com/websockets/ws) to 8.18.0 and updates ancestor dependency [@mermaid-js/mermaid-cli](https://github.com/mermaid-js/mermaid-cli). These dependencies need to be updated together.


Updates `ws` from 8.13.0 to 8.18.0
- [Release notes](https://github.com/websockets/ws/releases)
- [Commits](websockets/ws@8.13.0...8.18.0)

Updates `@mermaid-js/mermaid-cli` from 10.9.1 to 11.2.0
- [Release notes](https://github.com/mermaid-js/mermaid-cli/releases)
- [Commits](mermaid-js/mermaid-cli@10.9.1...11.2.0)

---
updated-dependencies:
- dependency-name: ws
  dependency-type: indirect
- dependency-name: "@mermaid-js/mermaid-cli"
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Bumps [activesupport](https://github.com/rails/rails) from 4.2.9 to 6.1.7.5.
- [Release notes](https://github.com/rails/rails/releases)
- [Changelog](https://github.com/rails/rails/blob/v7.2.1/activesupport/CHANGELOG.md)
- [Commits](rails/rails@v4.2.9...v6.1.7.5)

---
updated-dependencies:
- dependency-name: activesupport
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>