Use of deprecated xlink:href in examples

Created by: HuggeK

Prerequisites

• I have searched for duplicate or closed issues
• I have validated any HTML to avoid common problems
• I have read the contributing guidelines

Describe the issue

For example, the example of Footers use <svg class="bi" width="30" height="24"><use xlink:href="#bootstrap"/></svg> to display the Bootstrap Logo. xlink:type is deprecated and should not be used acording to Mozilla.

Reduced test cases

https://getbootstrap.com/docs/5.1/examples/footers/

What operating system(s) are you seeing the problem on?

Windows

What browser(s) are you seeing the problem on?

Chrome

What version of Bootstrap are you using?

v5.1.0