docs: fix code highlighting (#14022)

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>
Co-authored-by: pasha-codefresh <pavel@codefresh.io>

mkdocs.yml

@@ -8,7 +8,8 @@ extra_javascript:
 - assets/versions.js
 markdown_extensions:
 - markdown_include.include
-- codehilite
+- codehilite:
+    css_class: highlight
 - admonition
 - toc:
     permalink: true