Document must have one main landmark and a All page content must be contained by landmarks in Axe validator when creating a modal

[jcmontoyar]

Describe the bug

When creating a modal with react bootstrap the axe valitator shows both issues in the title.

To Reproduce

Steps to reproduce the behavior:

1. Create any modal or just go to the modal component in the react documentation
2. Inspect element in google chrome
3. Run axios validator
4. Both issues will appear

Environment (please complete the following information)

• Operating System: windows 10
• Browser, Version [e.g. Chrome 86]
• React-Bootstrap Version 1.4.0

[kyletsang]

Looks like upstream bootstrap has removed role="document" from the modal in twbs/bootstrap#30687. We should do the same here.