Correction to "extend" property name in release notes

Fixes issue #2320

Author: phil-davis

package.xml

@@ -47,7 +47,7 @@ http://pear.php.net/dtd/package-2.0.xsd">
     -- Thanks to Juliette Reinders Folmer for the help with this patch
   - Array properties set inside a ruleset.xml file can now extend a previous value instead of always overwriting it
     -- e.g., if you include a ruleset that defines forbidden functions, can you now add to that list instead of having to redefine it
-    -- To use this feature, add extends="true" to the property tag
+    -- To use this feature, add extend="true" to the property tag
        --- e.g., property name="forbiddenFunctionNames" type="array" extend="true"
     -- Thanks to Michael Moravec for the patch
   - If $XDG_CACHE_HOME is set and points to a valid directory, it will be used for caching instead of the system temp directory