[css2] Added text saying that CSS 2.1 overrides CSS2 for all features thay

have in common.

--HG--
extra : convert_revision : svn%3A73dc7c4b-06e6-40f3-b4f7-9ed1dbc14bfc/trunk%402266

Author: bert-github

css2/cover.src

@@ -102,6 +102,13 @@ But most of all CSS 2.1
 represents a "snapshot" of CSS usage: it consists of all CSS features
 that are implemented interoperably at the date of publication of the Recommendation.
 
+<p>CSS&nbsp;2.1 is derived from and is intended to replace CSS2. Some
+parts of CSS2 are unchanged in CSS&nbsp;2.1, some parts have been
+altered, and some parts removed. The removed portions may be used in a
+future CSS3 specification. Implementations may refer to CSS2 for the
+definitions of features that have been removed, but for other features
+CSS&nbsp;2.1 is the normative reference.
+
 <h2 id=status>Status of this document</h2>
 
 <p><em>This section describes the status of this document at the time