Add policy reference

[lukefretwell]

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Would be great to link validation parameters to policy.

Working doc: https://docs.google.com/document/d/1Cs4C81y9WDlEnWmqz_A0jdvrXt0ZbVqxxmHy6dn-rUE/edit?usp=sharing

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Add policy to documentation (review guidance and determine whether to modify that or have in addition to policy).

• Create policy pages
• Reference related policies for each validation parameter below status ('Policy' h2).
• Add policy validation parameter that grades/scores overall adherence?
• /policy with results page of policies
• Policy tab or link in footer
• Policy page on documentation?

Describe alternatives you've considered
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N/A

Additional context
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Thoughts on policy page:

H1: number or title
Description : title?
Agency issued
Date issued
Link to policy (original source) and full text and/or pdf on ScanGov

Indicator pages

• If indicator is part of a policy
• Link to policy (or directly to reference)