Markdown meta data

• date: meta[property="article:published_time
• modified: meta[property="og:updated_time and article:modified_time
• slug: {string}
• type: page|post|portfolio
• header: image string on Cloudinary
• headerColofon: header image attribution
• headerClassName: ''|no-blur|darken
• categories
• tags
• description: 160 characters description
• metaKeyword
• id
• excerpt
• metaTitle
• metaDescription

type=blog extra properties

• sticky: true|false
• related: space delimited slugs

type=portfolio extra properties

• excerpt: string
• excerptNl: string
• clients: string[]
• collaboration: string[]
• prizes: string[]
• thumbnail: string[]
• image: string
• images: string[]
• inCv: true|false
• inPortfolio: true|false
• dateFrom: /\d{4}-\d\d-\d\d/
• dateTo: /\d{4}-\d\d-\d\d/