Use angle bracket delimited shortcodes to fix h2 anchors

[klingtnet]

Since hugo 0.55 percent sign delimited shortcodes were interpreted as
markdown which caused our <h2> headings to be dropped silently.

To get the old behavior you can either prepend your shortcode template
with

{{ $_hugo_config := `{ "version": 1 }` }}

or use the {{< my-shortcode > }} format. The latter one is explicit
and thus clearer. (Details)

It boggles my mind that they introduced a breaking
change like this and then also allowed to override the behavior of one
format, now it is unclear how a short code is handled until you know
its template definition.

[miku]

thanks for digging into this - indeed an unpleasant issue