Adding option to configure HTTP proxy for Metadata service

Change-Id: I14926f047701c0e37de05bfe6a3aa41b786d001f
diff --git a/README.rst b/README.rst
index c079e06..daff9cb 100644
--- a/README.rst
+++ b/README.rst
@@ -43,3 +43,15 @@
         aN5DvAdir7oYCpHwD5/WvHahUgsrtcz9s+pzRfiStvICVwqCsGquThZHe8YAgGpZ
         04UU/56ncPbsHf5asS3DvfVGw==
         -----END CERTIFICATE-----
+
+
+Shibboleth through HTTP proxy
+==============
+Sometimes there is needed to connect to IdP through HTTP proxy. This has to be done via adding TransportOption to MetadataProvider in Shibboleth2.xml configuration file.
+
+.. code-block:: yaml
+
+  shibboleth:
+    server:
+      enabled: true
+      proxy: http://10.10.10.12:8888
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