Fix reference to puppet-pull for syncing the nodes

The documentation refers to a puppet-run instead of puppet-pull command
because of a misprint.

The puppet-pull script was introduced into fuel-library with:
https://review.openstack.org/#/c/63950/

Closes-Bug: 1364886
Change-Id: I546550e7858d1d03de0931ff777802e5b141fd04
Merge "Fix reference to puppet-pull for syncing the nodes"