Update release notes for PDB 2.2.1 release.
Update release notes for PDB 2.2.1 release.

wkalt/puppetdb,highb/puppetdb,rbrw/puppetdb,rbrw/puppetdb,rbrw/puppetdb,kbarber/puppetdb,rbrw/puppetdb,rbrw/puppetdb,waynr/puppetdb,johnduarte/puppetdb,ajroetker/puppetdb,highb/puppetdb,mullr/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,kbrezina/puppetdb,grimradical/puppetdb,ajroetker/puppetdb,waynr/puppetdb,shrug/puppetdb,kbarber/puppetdb,wkalt/puppetdb,highb/puppetdb,waynr/puppetdb,shrug/puppetdb,waynr/puppetdb,kbarber/puppetdb,shrug/puppetdb,highb/puppetdb,mullr/puppetdb,mullr/puppetdb,puppetlabs/puppetdb,kbarber/puppetdb,johnduarte/puppetdb,kbrezina/puppetdb,johnduarte/puppetdb,johnduarte/puppetdb,grimradical/puppetdb,grimradical/puppetdb,senior/puppetdb,ajroetker/puppetdb,senior/puppetdb,mullr/puppetdb,wkalt/puppetdb,ajroetker/puppetdb,senior/puppetdb,grimradical/puppetdb,mullr/puppetdb,senior/puppetdb,kbrezina/puppetdb,kbrezina/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,shrug/puppetdb,wkalt/puppetdb