(maint) Update other docs links in the release notes
(maint) Update other docs links in the release notes

These should make it easier for the user to navigate to the important
new parts of our docs.

puppetlabs/puppet-server,puppetlabs/puppet-server,puppetlabs/puppetserver,puppetlabs/puppetserver,puppetlabs/puppetserver,puppetlabs/puppet-server,puppetlabs/puppetserver