docs: Prepare for new sub tree

See #11925

docs/content/en/methods/page/TranslationKey.md

@@ -1,74 +0,0 @@
----
-title: TranslationKey
-description: Returns the translation key of the given page.
-categories: []
-keywords: []
-action:
-  related:
-   - methods/page/Translations
-   - methods/page/AllTranslations
-   - methods/page/IsTranslated
-  returnType: string
-  signatures: [PAGE.TranslationKey]
----
-
-The translation key creates a relationship between all translations of a given page. The translation key is derived from the file path, or from the `translationKey` parameter if defined in front matter.
-
-With this site configuration:
-
-{{< code-toggle file=hugo >}}
-defaultContentLanguage = 'en'
-
-[languages.en]
-contentDir = 'content/en'
-languageCode = 'en-US'
-languageName = 'English'
-weight = 1
-
-[languages.de]
-contentDir = 'content/de'
-languageCode = 'de-DE'
-languageName = 'Deutsch'
-weight = 2
-{{< /code-toggle >}}
-
-And this content:
-
-```text
-content/
-├── de/
-│   ├── books/
-│   │   ├── buch-1.md
-│   │   └── book-2.md
-│   └── _index.md
-├── en/
-│   ├── books/
-│   │   ├── book-1.md
-│   │   └── book-2.md
-│   └── _index.md
-└── _index.md
-```
-
-And this front matter:
-
-{{< code-toggle file=content/en/books/book-1.md fm=true >}}
-title = 'Book 1'
-translationKey = 'foo'
-{{< /code-toggle >}}
-
-{{< code-toggle file=content/de/books/buch-1.md fm=true >}}
-title = 'Buch 1'
-translationKey = 'foo'
-{{< /code-toggle >}}
-
-When rendering either either of the pages above:
-
-```go-html-template
-{{ .TranslationKey }} → page/foo
-```
-
-If the front matter of Book 2, in both languages, does not include a translation key:
-
-```go-html-template
-{{ .TranslationKey }} → page/books/book-2
-```