[e] (0) add note about db versions

git-svn-id: http://svn.whatwg.org/webapps@1092 340c8d12-0b0e-0410-8428-c7bf67bfef74

index

@@ -30408,6 +30408,12 @@ have a variable and unknownable number of literals coming:
    databases. Each database has a name and a current version. There is no way
    to enumerate or delete the databases available for a domain from this API.
 
+  <p class=note>Each database has one version at a time, a database can't
+   exist in multiple versions at once. Versions are intended to allow authors
+   to manage schema changes incrementally and non-destructively, and without
+   running the risk of old code (e.g. in another browser window) trying to
+   write to a database with incorrect assumptions.
+
   <p>The <dfn id=opendatabase
    title=dom-opendatabase><code>openDatabase()</code></dfn> method returns a
    <code><a href="#database0">Database</a></code> object. The method takes

source

@@ -27996,6 +27996,13 @@ have a variable and unknownable number of literals coming:
   enumerate or delete the databases available for a domain from this
   API.</p>
 
+  <p class="note">Each database has one version at a time, a database
+  can't exist in multiple versions at once. Versions are intended to
+  allow authors to manage schema changes incrementally and
+  non-destructively, and without running the risk of old code (e.g. in
+  another browser window) trying to write to a database with incorrect
+  assumptions.</p>
+
   <p>The <dfn
   title="dom-opendatabase"><code>openDatabase()</code></dfn> method
   returns a <code>Database</code> object. The method takes two