[CONFIGURATION-610] Fixed examples in user guide for PropertiesConfiguration.
[CONFIGURATION-610] Fixed examples in user guide for PropertiesConfiguration.

In these examples an incorrect generic type was used for configuration
builders.

git-svn-id: 0d31da9e303333003508381311333cf78a25d41b@1715284 13f79535-47bb-0310-9956-ffa450edef68

apache/commons-configuration,apache/commons-configuration,apache/commons-configuration