manual: refine ECMA-335 reference for attributes

Author: emberian

src/doc/rust.md

@@ -1685,10 +1685,10 @@ attr : ident [ '=' literal
 ~~~~
 
 Static entities in Rust -- crates, modules and items -- may have _attributes_
-applied to them. Attributes in Rust are modeled on Attributes in ECMA-335, C#.
-An attribute is a general, free-form metadatum that is interpreted according
-to name, convention, and language and compiler version.  Attributes may appear
-as any of:
+applied to them. Attributes in Rust are modeled on Attributes in ECMA-335,
+with the syntax coming from ECMA-334 (C#). An attribute is a general,
+free-form metadatum that is interpreted according to name, convention, and
+language and compiler version. Attributes may appear as any of:
 
 * A single identifier, the attribute name
 * An identifier followed by the equals sign '=' and a literal, providing a
@@ -1881,8 +1881,8 @@ For any lint check `C`:
  * `deny(C)` signals an error after encountering a violation of `C`,
  * `allow(C)` overrides the check for `C` so that violations will go
     unreported,
- * `forbid(C)` is the same as `deny(C)`, but also forbids uses of
-   `allow(C)` within the attribute.
+ * `forbid(C)` is the same as `deny(C)`, but also forbids changing the lint
+    level afterwards.
 
 The lint checks supported by the compiler can be found via `rustc -W help`,
 along with their default settings.