We were using `yaml.Unmarshal` on basic types or inline structs. This
was not efficient and not clear to defined what we expect in labels.
We now use types to unmarshal the labels.
Only the `values` label is, at this time, parsed by GetValuesFromLabel
because this `utils` function is clearly a special case.
- better gomarkdown generation that now fixed the escaped strings, no
need to use pandoc anymore
- added workflow image
- upgraded versions of mkdocs requirements
