(SIMP-8480) Update changelog for 2 components + use roles (#399)

* (SIMP-8480) Update changelog for latest simp/simp

Changelog updates:
* Entries for latest released version of simp/simp
* Entries for released version of simp/tftpboot. Removed discussion
  of a change that was reverted (rsync permissions).
* Fixed a few typos/unclear passages.
* Standardized reference to hiera as "Hiera" to match Puppet
  documentation.
* Used new Sphinx roles. Wasn't sure what to do with a couple of
  types of text that are not covered by the current set of roles.

  * Snippets of text emitted from a warning message:  Used double
    backticks.
  * Facts: Used :code:
  * Strings that would end up in application configuration files:
    Used single quotes.
  * YAML keys: Used single quotes except when talking about adding
    a class to `simp:classes` in Hiera.
  * Dynamic libraries: Used single quotes.
  * Puppet environment name: Used single quotes

* Fix reference to simp/hirs_provisioner

SIMP-8480 #comment 2nd update