Add haystack.utils API docs (#7311)

docs/pydoc/config/utils_api.yml

@@ -0,0 +1,27 @@
+loaders:
+  - type: haystack_pydoc_tools.loaders.CustomPythonLoader
+    search_path: [../../../haystack/utils]
+    ignore_when_discovered: ["__init__", "hf"]
+processors:
+  - type: filter
+    expression:
+    documented_only: true
+    do_not_filter_modules: false
+    skip_empty_modules: true
+  - type: filter
+    expression: "name not in ['TokenSecret', 'EnvVarSecret','_get_default_device', '_split_device_string', 'convert']"
+  - type: smart
+  - type: crossref
+renderer:
+  type: haystack_pydoc_tools.renderers.ReadmePreviewRenderer
+  excerpt: Utils API
+  category_slug: haystack-api
+  title: Utils API
+  slug: utils-api
+  order: 153
+  markdown:
+    descriptive_class_title: false
+    descriptive_module_title: true
+    add_method_class_prefix: true
+    add_member_class_prefix: false
+    filename: utils_api.md