PuppetDB toc: Add new v4 end-points to master index

We have added v4 elements to the source documentation, this adds the links to
the ToC as well.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #302 from kbarber/maint/master/add-v4-to-puppetdb-toc

PuppetDB toc: Add new v4 end-points to master index