chore: agents md note

Signed-off-by: Christian Stewart <christian@aperture.us>

Author: paralin

AGENTS.md

@@ -13,6 +13,7 @@ Fix anything that you come across in the project while working that violates any
 - Condense and consolidate duplicates into a single authoritative section
 - Ensure guidelines are clear and non-contradictory
 - NEVER run the vite dev server or anything that listens on any port yourself! Ask the user to do it!
+- Read `docs/explainer.md` for an overview of the project if you need it
 
 Remember to always delete dead code when changing things - for example if you changed something and a function is no longer used anywhere, delete that function.