(MAINT) Add http-client metrics-enabled setting to puppetserver.conf doc
(MAINT) Add http-client metrics-enabled setting to puppetserver.conf doc

This commit adds info for the new metrics-enabled setting in the
http-client section of the puppetserver.conf file to the
config_file_puppetserver.markdown doc.

er0ck/puppetserver,camlow325/puppetserver,camlow325/puppetserver,er0ck/puppetserver,camlow325/puppetserver,puppetlabs/puppet-server,camlow325/puppet-server,camlow325/puppet-server,puppetlabs/puppetserver,er0ck/puppetserver,puppetlabs/puppetserver,camlow325/puppet-server,puppetlabs/puppet-server,er0ck/puppetserver,puppetlabs/puppet-server,camlow325/puppetserver,puppetlabs/puppetserver,puppetlabs/puppetserver