I would like to be able host Boostrap docs on subpath

[kant2002]

Prerequisites

• I have searched for duplicate or closed feature requests
• I have read the contributing guidelines

Proposal

I would like to modify infrastructure to the current docs, to be "publishable" to both root domain, like https://getbootstrap.com/ and to subfolders, like https://kant2002.github.io/custom-bootstrap/

Motivation and context

Motivation for this feature, is to promote more of custom themes with docs. Maybe small teams, can take existing Bootstrap, and ship custom version without thinking where to deploy TOO much, right now my customizations was quite extensive and I do not sure that that's all what's needed.

I really appreciate that current bootstrap goes as far, as it currently is with creation of custom themes, but maybe I'm a bit geedy and want to be able use GitHub pages for such deployments.

Probably that's not huge win, but rather accommodation to these who think about having custom theme.