make directories examples real puppet DSL

People don't read:

    directory => [ { path => '/path/to/directory', <directive> => <value> } ],

as psuedo-code example instructing you on how to form an array of hashes, they
read them as puppet DSL examples that they can copy and paste into their
apache::vhost stanzas.
Merge pull request #253 from richardc/vhost_directories_usage

make directories examples real puppet DSL