Rewrite README per DOC-1499
Rewrite README per DOC-1499

1. Remove any "what this affects" sections, except where particularly warranted.
2. Make sure that for each parameter, where applicable, there is a data type and a default value.
3. Make sure that for each parameter that's applicable, there is a note if the parameter is optional.
4. Make sure the links in the README work and are accurate.
5. Update the link in the Contributing section to point here: https://docs.puppetlabs.com/forge/contributing.html
6. General copyediting.

zoojar/puppetlabs-haproxy,natewarr/puppetlabs-haproxy,MelanieGault/puppetlabs-haproxy,icg-puppet/puppetlabs-haproxy,x-way/puppetlabs-haproxy,rdo-puppet-modules/puppetlabs-haproxy,jpadams/puppetlabs-haproxy,automaticserver/puppet-haproxy,redhat-cip/puppetlabs-haproxy,jpadams/puppetlabs-haproxy,oshaughnessy/puppetlabs-haproxy,automaticserver/puppet-haproxy,oshaughnessy/puppetlabs-haproxy,puppetlabs/puppetlabs-haproxy,DavidS/puppetlabs-haproxy,exo-puppet/puppetlabs-haproxy,natewarr/puppetlabs-haproxy,puppetlabs/puppetlabs-haproxy,redhat-cip/puppetlabs-haproxy,rdo-puppet-modules/puppetlabs-haproxy,MelanieGault/puppetlabs-haproxy,tphoney/puppetlabs-haproxy,tphoney/puppetlabs-haproxy,gwdg/puppetlabs-haproxy,DSI-Ville-Noumea/puppetlabs-haproxy,icg-puppet/puppetlabs-haproxy,gwdg/puppetlabs-haproxy,x-way/puppetlabs-haproxy,fuel-infra/puppetlabs-haproxy,zoojar/puppetlabs-haproxy,DSI-Ville-Noumea/puppetlabs-haproxy,DavidS/puppetlabs-haproxy,exo-puppet/puppetlabs-haproxy,puppetlabs/puppetlabs-haproxy,blackcobra1973/puppetlabs-haproxy,fuel-infra/puppetlabs-haproxy,blackcobra1973/puppetlabs-haproxy