In order to configure a template, I would like to add properties to the header section of a (blog) page. When I add foo: bar and add {{ page.header.foo }} into the template, nothing is shown, but when I add, say, {{ page.header.pagination }} into the template 1 is shown (the blag has pagination:true). Is there a way to add custom header fields? The docs are unclear.
The significance of these headers is that Grav does not use them by default, they are only read by the [ in this case ] sitemap plugin to determine how often this particular page is modified and what its priority should be.
Any page header such as this should be documented, and generally there will be some default value that will be used if the page does not provide it
Does this mean custom headers are not provided to grav at all? How or where should this be documented? Does this mean I can only configure templates if I build a plugin?