Update nist-sp-800-53-r5.md

Enterprises are getting caught up in trying to meet the MS version of these controls and we need to help them understand that it is OK and encouraged to tailor this approach to meet their needs.

Author: softcraftsman

articles/governance/policy/samples/nist-sp-800-53-r5.md

@@ -33,6 +33,16 @@ initiative definition.
 > definitions for this compliance standard may change over time. To view the change history, see the
 > [GitHub Commit History](https://github.com/Azure/azure-policy/commits/master/built-in-policies/policySetDefinitions/Regulatory%20Compliance/NIST_SP_800-53_R5.json).
 
+>[!IMPORTANT]
+> These Azure Policies are an opinionated view of implementing the NIST 800-53 Rev. 5 controls. Not
+> every policy may be required to meet the controls for your organization. This initiative assumes
+> your orgnization is using Microsoft tools and properties. Some policies may prefer some Azure features
+> over other Azure features that equally implement the security required to meet the controls.
+> This is a choice the Enterprise can make by creating their own initiative.
+> 
+> As such, most enterprises will need to create their own version of this initative and tailor it 
+> to their environment and replace some polices with custom versions to implement the controls required. 
+
 ## Access Control
 
 ### Policy and Procedures