Update the root-only test count in the note description

AGENTS.md

@@ -33,8 +33,8 @@ Inside an area, relative imports of siblings and subfolders are free. `../`
 is banned in every file, owned or not
 (`import/no-relative-parent-imports`). Files no alias owns need no `index.ts`
 and no alias, and import `./` siblings and subfolders freely. The one alias
-is `#testing` (`./src/testing/index.ts`): every test imports it by alias, and
-`tests/` reaches `src/` only through it. Local convention, stricter than the
+is `#testing` (`./src/testing/index.ts`): tests that use its helpers import
+it by alias, and `tests/` reaches `src/` only through it. Local convention, stricter than the
 general rule above: in this repo, aliases point only at a direct subfolder of
 `src/` (`"#helpers": "./src/helpers/index.ts"`), and code outside `src/` uses
 `./` relative imports. `scripts/` is flat: one file per