Update routing documentation (#1738)

Works towards #1531 

Some parts of the old outing docs will need to be included on the
`parameters` and `swagger-ui` pages which we still need to add.

docs/conf.py

@@ -111,6 +111,17 @@ try:
     html_theme = "sphinx_rtd_theme"
 
     html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
+
+    html_theme_options = {
+        'navigation_depth': 2
+    }
+
+    html_context = {
+        'display_github': True,
+        'github_user': 'spec-first',
+        'github_repo': 'connexion',
+        'github_version': 'main/docs/',
+    }
 except:
     pass
 
@@ -141,7 +152,11 @@ except:
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-# html_static_path = ['_static']
+html_static_path = ['_static']
+
+html_css_files = [
+    'css/default.css',
+]
 
 # Add any extra paths that contain custom files (such as robots.txt or
 # .htaccess) here, relative to this directory. These files are copied