Changed "maxValidityInterval" to P6D

Author: malavolti

idem-fedops/HOWTO-Shibboleth/Identity Provider/CentOS/HOWTO Install and Configure a Shibboleth IdP v3.4.x on CentOS 7 with Apache2 + Jetty9.md

@@ -1190,7 +1190,7 @@ Translate the IdP messages in your language:
            Require a validUntil XML attribute on the root element and
            make sure its value is no more than 10 days into the future.
          -->
-         <MetadataFilter xsi:type="RequiredValidUntil" maxValidityInterval="P10D"/>
+         <MetadataFilter xsi:type="RequiredValidUntil" maxValidityInterval="P6D"/>
 
          <!-- Consume all SP metadata in the aggregate -->
          <MetadataFilter xsi:type="EntityRoleWhiteList">