docs tweaks

Author: willmcgugan

docs/api/dom_node.md

@@ -1 +1,5 @@
+---
+title: "textual.dom"
+---
+
 ::: textual.dom

mkdocs-common.yml

@@ -67,11 +67,12 @@ plugins:
   search:
   autorefs:
   mkdocstrings:
-    custom_templates: docs/_templates
     default_handler: python
     handlers:
       python:
         options:
+          show_symbol_type_heading: true
+          show_symbol_type_toc: true
           show_signature_annotations: false
           separate_signature: true
           merge_init_into_class: true