[Docs v3] Typo in Modal Example

Created by: LKaemmerling

Hello,

i found an "typo" in the Docs for v3.3.7.

In the example is the class: "bs-example-modal-lg" (and "bs-example-modal-sm") used. If you copy & paste this example, it doesn't work. The right classes are "modal-lg" and "modal-sm".