docs(formatter_json): update AGENTS.md (#22976)

crates/oxc_formatter_json/AGENTS.md

@@ -11,8 +11,9 @@ Prettier compatible JSON/JSONC/JSON5 formatter (`oxfmt`'s Tier 1 backend), using
   - For Prettier, JSON is not spec compliant JSON
   - They are subsets of JS expression syntax, so the comments, unquoted key, etc... are allowed as input
 - A simplified, independent reimplementation that does not share `oxc_formatter`'s code
-  - But JSON is a subset of JS, so `oxc_formatter` (`crates/oxc_formatter/`) is the canonical reference
-  - For layout / comment / blank-line decisions when the simplified version is unclear or diverges from Prettier
+  - As a result, although Prettier's JSON (especially JSON5) behaves like JS, as a formatter implementation, they should be distinguished and kept from interfering with each other
+  - So, just use `oxc_formatter` (`crates/oxc_formatter/`) as the canonical reference
+    - For layout / comment / blank-line decisions when the simplified version is unclear or diverges from Prettier
 
 ### `JsonVariant`