Improve code blocks configuration

Enables:

* Highlighting specific lines:
  https://squidfunk.github.io/mkdocs-material/reference/code-blocks/#highlighting-specific-lines

* Add a pygments language class, so the style can be customized per
  language:
  https://squidfunk.github.io/mkdocs-material/setup/extensions/python-markdown-extensions/#+pymdownx.highlight.pygments_lang_class

* Make each line of a block linkeable:
  https://squidfunk.github.io/mkdocs-material/setup/extensions/python-markdown-extensions/#+pymdownx.highlight.anchor_linenums

* Add a span per line (only necessary for the features above to work):
  https://squidfunk.github.io/mkdocs-material/setup/extensions/python-markdown-extensions/#+pymdownx.highlight.line_spans

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

cookiecutter/{{cookiecutter.github_repo_name}}/mkdocs.yml

@@ -67,6 +67,10 @@ markdown_extensions:
   - admonition
   - attr_list
   - pymdownx.details
+  - pymdownx.highlight:
+      anchor_linenums: true
+      line_spans: __span
+      pygments_lang_class: true
   - pymdownx.snippets:
       check_paths: true
   - pymdownx.superfences: