Add missing topics to puppetdb index

This includes:

* KahaDB corruption - which introduces the new troubleshooting section
* Migrating Data - which documents the new export/import tooling

Previously these were only linked from other documents but not in the index
itself.

Signed-off-by: Ken Barber <ken@bob.sh>
Fix cut & paste issues

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #159 from kbarber/puppetdb_add_migrate_to_index

Add missing topics to puppetdb index