feat: parse markers

[tenstad]

Parses all CRD markers so that e.g. default and validation markers may be used to generate doc.

The markers are not used for anything right now, but can be seen by adding {{ $type.Markers}} and {{ .Markers }} in type.tpl, which results in:

#### Guestbook
map[kubebuilder:object:root:[true] kubebuilder:subresource:status:[{}]]

#### Rating
map[kubebuilder:validation:Maximum:[5] kubebuilder:validation:Minimum:[1]]

| `page` _integer_ | Page indicates the page number | map[kubebuilder:default:[{1}]]

| `a` _[Underlying1](#underlying1)_ |  | map[kubebuilder:default:[{b}]]

[tenstad]

@thbkrkr to keep it clean, I think we should merge this one as is, without doing anything with the markers just yet. WDYT?

[thbkrkr]

@thbkrkr to keep it clean, I think we should merge this one as is, without doing anything with the markers just yet. WDYT?

Yes, that sounds good to me.

[mowies]

@thbkrkr @tenstad any plans on when this will be released? Really looking forward to it! 🎉

[thbkrkr]

@mowies It's released: https://github.com/elastic/crd-ref-docs/releases/tag/v0.0.10.

[mowies]

Thanks! 🙌🏼