Make CI-builds more visually distinctive

[lmckenzi]

Not clear if this is a publisher thing or a template thing or a bit of both.

https://jira.hl7.org/browse/FHIR-46536 suggests that we should make the CI builds more visually distinct from official releases. For example, some sort of an "under construction" symbol visible when looking at the content of the IG, or a color shift, or perhaps both.

[costateixeira]

the Belgian template does it based on status: https://github.com/hl7-be/hl7.be.fhir.template/blob/master/includes/_append.fragment-css.html

The WHO template does something more complete - remove the logo and add a visible watermark: https://worldhealthorganization.github.io/smart-example-immz/