Add documentation for Wrapper into `theano/doc/library/gof`.

doc/library/gof/index.txt

@@ -17,4 +17,5 @@
     fgraph
     toolbox
     type
+    wrapper
     utils

doc/library/gof/wrapper.txt

+.. _libdoc_gof_wrapper:
+
+=============================================
+:mod:`wrapper` -- Wrapper class for op params
+=============================================
+
+---------
+Reference
+---------
+
+.. automodule:: theano.gof.wrapper
+   :platform: Unix, Windows
+   :synopsis: Wrapper class for op params
+   :members:
+.. moduleauthor:: LISA
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