inferred.md: add missing id
diff --git a/src/types/inferred.md b/src/types/inferred.md
index 08964f9..370b9b1 100644
--- a/src/types/inferred.md
+++ b/src/types/inferred.md
@@ -13,6 +13,7 @@
 r[type.inferred.constraint]
 It cannot be used in item signatures.
 
+r[type.inferred.usage]
 It is often used in generic arguments:
 
 ```rust