fix misleading typo in documentation

# Syntax:

#

#     su_apache::cert::comodo { "<hostname>":

#     su_apache::cert::incommon { "<hostname>":

#         ensure      => present,

#         keyname     => "ssl-key/<hostname>",

#         owner       => "root",

# $identity: If the file name in the cert_files module does NOT match $name, you can specify

# the file name with $identity. Example:

#

# su_apache::cert::comodo { 'example.stanford.edu':

# su_apache::cert::incommon { 'example.stanford.edu':

#   identity => 'example2.stanford.edu',

# }

#