Add reference numbers to Azure Resource Manager Templates - Best Practices Guide

Specific requirements of the 'Azure Resource Manager Templates - Best Practices Guide' are referenced in PRs that fail validation.
It is difficult to find the section referenced based on the PR text.

https://github.com/Azure/azure-quickstart-templates/blob/master/1-CONTRIBUTION-GUIDE/best-practices.md#best-practices

Please add at least section and paragraph numbers to this document to align with other requirements documents Microsoft uses.

I would also recommend renaming this from 'Best Practices' to 'Requirements' since if they are not followed the submission fails. If not all guidelines are requirements, then each guideline should be more specific to whether it is a guideline or a requirement.

Open 1-CONTRIBUTION-GUIDE/best-practices.md and review the Best Practices section referenced by validation-failure PRs. Add section and paragraph numbers so those references are easy to locate, then resolve whether the document should be renamed to Requirements or whether each item should be labeled as a guideline or requirement.

Written by the indexing model from the issue text.