Introduces a new Hugo shortcode, `includeRegion`, to allow embedding
specific, tagged regions from source files directly into Markdown
content.
This helps maintain a single source of truth for code snippets and other
repeated content, such as setup instructions, preventing duplication and
simplifying updates across multiple quickstart guides.
Demo PR: https://github.com/googleapis/genai-toolbox/pull/1179
---------
Co-authored-by: Anmol Shukla <shuklaanmol@google.com>
