Complete output for get_taxonomy in the documentation (#2204)

Complete the documentation for the output of the tera function
`get_taxonomy` to include the `lang` and `permalink` overlooked fields.

Co-authored-by: Xavier B <>

docs/content/documentation/templates/overview.md

@@ -172,6 +172,8 @@ The type of the output is:
 ```ts
 kind: TaxonomyConfig;
 items: Array<TaxonomyTerm>;
+lang: String;
+permalink: String;
 ```
 
 `lang` (optional) default to `config.default_language` in config.toml