Fixed example for hero deprecation (#2567)
Fixed example for hero deprecation (#2567)

- If  the `custom_dir` is `overrides` (as specified  in the documentation) it shouldn't be specified in the template path
- `{% extends "base.html" %}` is needed in the template
squidfunk/mkdocs-material,squidfunk/mkdocs-material,squidfunk/mkdocs-material,squidfunk/mkdocs-material