Customizable docs implementation

[jhgilbert]

What does this PR do? What is the motivation?

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• [ ] Please merge after reviewing

Additional notes

[github-actions[bot]]

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New or renamed files

• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/demos/colors/primaryoc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/demos/colors/primary_control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/demos/colors/traffic_lightoc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/demos/debug_it/
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/demos/debug_it/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/demos/debug_it/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/demos/postgres_setup/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/demos/postgres_setup/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/alert/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/alert/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/callout/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/callout/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/code_block/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/code_block/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/description_list/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/description_list/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/further_reading/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/further_reading/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/image_or_video/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/image_or_video/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/region_param/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/region_param/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/site_region/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/site_region/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/table/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/table/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/tabs/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/tabs/control
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/whatsnext/oc
• https://docs-staging.datadoghq.com/jen.gilbert/customizable-docs-implementation/markdoc/tags_and_elements/whatsnext/control