feat(forge doc): add --watch flag

[Metaxona]

Component

Forge

Describe the feature you would like

allow --watch flag on forge doc to allow live updates on documentation changes

it would be good to have a live updates on doc changes when I update my contract instead of doing a build and serve every time

Additional context

No response

[francesco-gaglione]

Working on this, I will publish a draft pull request to propose a solution idea to be taken as a basis for implementing this functionality.