Fix hash.pp doc (#159)

#

# [*name*]    - the name of the map file.

# [*ensure*]  - present/absent, defaults to present.

# [*source*] - file source.

# [*source*]  - file source. Mutially exclusive with "content".

# [*content*] - content of the file. Mutially exclusive with "soruce".

#

# === Requires

#

#

# === Examples

#

#   postfix::hash { '/etc/postfix/virtual':

#   postfix::hash { 'virtual':

#     ensure => present,

#   }

#   postfix::config { 'virtual_alias_maps':