Apply suggestion from @jedbrown

Co-authored-by: Jed Brown <jed@jedbrown.org>

Author: lwasser

appendices/gen-ai-checklist.md

@@ -1,6 +1,6 @@
 ```markdown
 - [ ] Parts of this package were created using LLMs.
-**Below, please describe how LLM's were used to develop this package's code and documentation.**
+**Below, please describe how LLMs were used to develop this package's code and documentation.**
 
 - [ ] I acknowledge that a human (at least one member of our maintainer team) has reviewed and edited all LLM-generated code and text submitted in this review to ensure it’s not biased (if text) and the code runs (if code).
 ```