Added documentation for AttributeCopy authentication processing filter.

docs/simplesamlphp-authproc.txt

@@ -128,6 +128,7 @@ The following filters are included in the simpleSAMLphp distribution:
 - [`authorize:Authorize`](./authorize:authorize): Access control based on regular expressions.
 - [`consent:Consent`](./consent:consent): Ask the user for consent before transmitting attributes.
 - [`core:AttributeAdd`](./core:authproc_attributeadd): Add attributes to the response.
+- [`core:AttributeCopy`](./core:authproc_attributecopy): Copy existing attributes to the response.
 - [`core:AttributeAlter`](./core:authproc_attributealter): Do search-and-replace on attributevalues.
 - [`core:AttributeLimit`](./core:authproc_attributelimit): Limit the attributes in the response.
 - [`core:AttributeMap`](./core:authproc_attributemap): Change the name of the attributes.

modules/core/docs/authproc_attributecopy.txt

+`core:AttributeCopy`
+===================
+
+Filter that renames attributes.
+
+
+Examples
+--------
+
+Copy a single attribute (user's uid will be copied to the user's username):
+
+    'authproc' => array(
+        50 => array(
+            'class' => 'core:AttributeCopy',
+            'uid' => 'username',
+        ),
+    ),
+