Update the best practices documentation to include simpler examples of of jinja dictionaries

[nbirnel]

Currently the best practices (http://docs.saltstack.com/en/latest/topics/best_practices.html) includes an example of a separate map.jinja file, with a merge
of pillar data. This is probably overkill for simpler use case scenarios. The best practices should
include a simple dictionary, eg:

{% set auditd = salt['grains.filter_by']({
  'RedHat': { 'package': 'audit' },
  'Debian': { 'package': 'auditd' },
}) %}

gravyboat asked me to add this issue after the first Seattle Saltstack user's meetup.

[jfindlay]

@nbirnel, thanks for the report.

[jacobhammons]

I added this example to the Understanding Jinja topic at https://docs.saltstack.com/en/latest/topics/jinja/index.html, it is at the bottom of the first section.

@nbirnel If you agree that this fixes the issue please close. Thanks!

[nbirnel]

@jacobhammons Thanks, that looks good to me.