feat(`forge doc`): replace the documentation generated from `mdbook` to `vocs`

[zerosnacks]

Component

Forge

Describe the feature you would like

To investigate what this would entail, the benefit is quite clear from other mdbook to vocs ports we've already done.

Related: https://getfoundry.sh/ + #9317

To investigate: how well does Solidity syntax highlighting work, what changes would be required in the formatter, etc.

cc @yash-atreya / @DaniPopes

Additional context

No response