manual: add 'item', remove statement that built-in types are keywords.

Author: graydon

doc/rust.md

@@ -2413,14 +2413,12 @@ The failure carries string representation of the false expression.
 
 ## Types
 
-Every slot and value in a Rust program has a type. The _type_ of a *value*
+Every slot, item and value in a Rust program has a type. The _type_ of a *value*
 defines the interpretation of the memory holding it.
 
 Built-in types and type-constructors are tightly integrated into the language,
 in nontrivial ways that are not possible to emulate in user-defined
-types. User-defined types have limited capabilities. In addition, every
-built-in type or type-constructor name is reserved as a *keyword* in Rust;
-they cannot be used as user-defined identifiers in any context.
+types. User-defined types have limited capabilities.
 
 ### Primitive types