[Low] Conflict message in build

[remibetin]

Jekyll build returns warning messages such as:

Conflict: The following destination is shared by multiple files.
The written file may end up with unexpected contents.
/opt/build/repo/_site/ARIA/apg/patterns/tabs/examples/tabs-actions/index.html

• ARIA/apg/patterns/tabs/examples/tabs-actions.md
• content/patterns/tabs/examples/tabs-actions.md

This is because there is a content symlink that refers to the ARIA folder.

In turn, there is a wai-aria-practices symlink in the wai-website repository that refers to the content folder in the submodule.

To simplify the setup and remove the warning, we could remove the content symlink in this repository and update the symlink in the wai-website directory to directly refer to the ARIA folder instead.