Fix up README for pgbouncer
Fix up README for pgbouncer

musicglue/heroku-buildpack-postgresql,gregburek/heroku-buildpack-postgresql,agriffis/heroku-buildpack-pgbouncer,realtymaps/heroku-buildpack-pgbouncer,davegwilt/heroku-buildpack-stunnel,BetterWorks/heroku-buildpack-pgbouncer,Yobota/heroku-buildpack-pgbouncer,timshadel/heroku-buildpack-stunnel,Shyp/heroku-buildpack-pgbouncer,rmoorman/heroku-buildpack-pgbouncer,heroku/heroku-buildpack-pgbouncer