added a note about the experimental 'zlib:' fopen wrapper

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@33806 c90b9560-bf6c-de11-be94-00142212c4b1

functions/zlib.xml

@@ -14,6 +14,21 @@
    with gzip-compressed files (and uncompressed files, too, but not
    with sockets).
   </para>
+  <note>
+   <para>
+    The current CVS version 4.0.4-dev introduces a fopen-wrapper
+    for .gz-files, so that you can use a special 'zlib:' URL to
+    access compressed files transparently using the normal 
+    f*() file access functions if you prepend the filename or path
+    with a 'zlib:' prefix when calling <function>fopen</function>.
+   </para>
+   <para>
+    This feature requires a C runtime library that provides the
+    <literal>fopencookie()</literal> function. To my current
+    knowledge the GNU libc is the only library that provides
+    this feature.
+   </para>
+  </note>
 
    <sect1 id="zlib-example">
     <title>Small code example</title>