Maintenance - Deprecate wiki #3327

It has been agreed upon that the wiki could be phased out in favor of main docs, as long as proper links are provided.

This is a reminder to:

• Comment or remove wiki links in main docs (started in Docs audit [April 2026]: Docs content update #3298)
• Verify that all wiki content has a matching/overlapping docs page with the right content
• Optionally, once other tasks are complete, disable/archive the wiki
• Edit mentions of "https://github.com/DeepLabCut/DeepLabCut/wiki/Using-labeled-data-in-DeepLabCut-that-was-annotated-elsewhere-(or-merge-across-labelers)" to point to the new recipe instead