doc: typo in dropdown options

Created by: Chaostheorie

In the docs for boostrap 5 (5.0 - See link below) the description of a javascript description is contradicting the defaullt on the left. Not too sure which is more accurate as the handling of defaults may vary between popper and bootstrap in e.g. navbar.

Specific Section: Dropdowns #Options

Specific conflicting option: boundary default: 'scrollParent' description: Overflow constraint boundary of the dropdown menu. By default it's 'clippingParents' and can accept an HTMLElement reference (JavaScript only).