Support Markdown in YAML

I would like to have markdown support in yaml configuration.
I want to modify the agency theme:
https://raw.githubusercontent.com/getgrav/grav-skeleton-agency-site/develop/pages/01.home/_services/services.md
Here I want to have a word in the text of the header: "Web Security" marked bold. At the moment markdown seems to be not honored in yaml. Is there a way to achieve this without making another sub-sub-page?

It's not exactly the same, but this plugin does this already:

https://github.com/nunopress/grav-plugin-metadata_extended

It looks to targets MetaData but it might work with other headers, or with a very slight modification it might :)

I found this in the docs: http://learn.getgrav.org/themes/twig-filters-functions#markdown
and it does exactly what I want.

{{ page.header.text|markdown}}

So maybe the plugin is not necessary at all?

sorry i completely misread your request i was thinking you wanted twig in the header yes markdown is simpler and you can just use the filter