docs: name the registries behind assets and dedup

The guides said files over 50 MB become release assets and that RPG Maker and ScummVM were the trees kept out of dedup. .gitignore decides the first, four committed files are over 50 MB, and NODEDUP_DIRS holds eleven trees.

tests/test_audit_regressions.py

@@ -5456,5 +5456,32 @@ class AnUnknownTargetIsRefusedUnderAll(unittest.TestCase):
         self.assertIn("retroarch", kept)
 
 
+class DocsDescribeTheRegistriesTheyName(unittest.TestCase):
+    """The contributing guide said files over 50 MB are release assets and that
+    RPG Maker and ScummVM were the trees kept out of dedup. `.gitignore`
+    decides the first, four committed files exceed 50 MB, and NODEDUP_DIRS
+    holds eleven trees."""
+
+    SIZE_RULE = re.compile(r"(over|larger than|>)\s*50\s*MB[^\n]*(release|asset)", re.I)
+
+    def _texts(self):
+        paths = sorted((ROOT / "wiki").glob("*.md"))
+        paths += [ROOT / "scripts" / "generate_readme.py", ROOT / "CONTRIBUTING.md"]
+        return [(p, p.read_text(encoding="utf-8")) for p in paths]
+
+    def test_no_page_says_size_decides_a_release_asset(self):
+        offenders = [str(p.relative_to(ROOT)) for p, text in self._texts()
+                     if self.SIZE_RULE.search(text)]
+        self.assertEqual(offenders, [])
+
+    def test_the_dedup_list_is_named_whole_or_by_its_constant(self):
+        from dedup import NODEDUP_DIRS
+        tools = (ROOT / "wiki" / "tools.md").read_text(encoding="utf-8")
+        line = next(l for l in tools.splitlines() if "NODEDUP_DIRS" in l)
+        self.assertEqual(sorted(d for d in NODEDUP_DIRS if d not in line), [])
+        readme_gen = (ROOT / "scripts" / "generate_readme.py").read_text(encoding="utf-8")
+        self.assertIn("NODEDUP_DIRS", readme_gen)
+
+
 if __name__ == "__main__":
     unittest.main()