Merge pull request #388 from SergioBenitez/master

Stabilize 'attr_literals' feature.

Author: Havvy

src/attributes.md

@@ -13,12 +13,12 @@
 > _MetaItem_ :\
 >       IDENTIFIER\
 >    | IDENTIFIER `=` LITERAL\
->    | IDENTIFIER `(` LITERAL `)`\
 >    | IDENTIFIER `(` _MetaSeq_ `)`
 >
 > _MetaSeq_ :\
 >       EMPTY\
 >    | _MetaItem_\
+>    | LITERAL\
 >    | _MetaItem_ `,` _MetaSeq_
 
 An _attribute_ is a general, free-form metadatum that is interpreted according
@@ -30,9 +30,8 @@ Attributes may appear as any of:
 * A single identifier, the _attribute name_
 * An identifier followed by the equals sign '=' and a literal, providing a
   key/value pair
-* An identifier followed by a parenthesized literal, providing a
-  key/value pair
 * An identifier followed by a parenthesized list of sub-attribute arguments
+  which include literals
 
 _Inner attributes_, written with a bang ("!") after the hash ("#"), apply to the
 item that the attribute is declared within. _Outer attributes_, written without