docs: Prepare for new sub tree

See #11925

docs/content/en/functions/openapi3/Unmarshal.md

@@ -1,76 +0,0 @@
----
-title: openapi3.Unmarshal
-description: Unmarshals the given resource into an OpenAPI 3 document.
-categories: []
-keywords: []
-action:
-  aliases: []
-  related: []
-  returnType: openapi3.OpenAPIDocument
-  signatures: ['openapi3.Unmarshal RESOURCE']
----
-
-Use the `openapi3.Unmarshal` function with [global], [page], or [remote] resources.
-
-[global]: /getting-started/glossary/#global-resource
-[page]: /getting-started/glossary/#page-resource
-[remote]: /getting-started/glossary/#remote-resource
-[OpenAPI]: https://www.openapis.org/
-
-For example, to work with a remote [OpenAPI] definition:
-
-```go-html-template
-{{ $url := "https://raw.githubusercontent.com/OAI/OpenAPI-Specification/main/examples/v3.0/petstore.json" }}
-{{ $api := "" }}
-{{ with resources.GetRemote $url }}
-  {{ with .Err }}
-    {{ errorf "%s" . }}
-  {{ else }}
-    {{ $api = . | openapi3.Unmarshal }}
-  {{ end }}
-{{ else }}
-  {{ errorf "Unable to get remote resource %q" $url }}
-{{ end }}
-```
-
-To inspect the data structure:
-
-```go-html-template
-<pre>{{ debug.Dump $api }}</pre>
-```
-
-To list the GET and POST operations for each of the API paths:
-
-```go-html-template
-{{ range $path, $details := $api.Paths }}
-  <p>{{ $path }}</p>
-  <dl>
-    {{ with $details.Get }}
-      <dt>GET</dt>
-      <dd>{{ .Summary }}</dd>
-    {{ end }}
-    {{ with $details.Post }}
-      <dt>POST</dt>
-      <dd>{{ .Summary }}</dd>
-    {{ end }}
-  </dl>
-{{ end }}
-```
-
-Hugo renders this to:
-
-
-```html
-<p>/pets</p>
-<dl>
-  <dt>GET</dt>
-  <dd>List all pets</dd>
-  <dt>POST</dt>
-  <dd>Create a pet</dd>
-</dl>
-<p>/pets/{petId}</p>
-<dl>
-  <dt>GET</dt>
-  <dd>Info for a specific pet</dd>
-</dl>
-```

docs/content/en/functions/openapi3/_index.md

@@ -1,12 +0,0 @@
----
-title: OpenAPI functions
-linkTitle: openapi3
-description: Template functions to work with OpenAPI 3 definitions.
-categories: []
-keywords: []
-menu:
-  docs:
-    parent: functions
----
-
-Use these functions to work with OpenAPI 3 definitions.