Optimize page: content/english/net/cad-technical-drawing-formats/_index.md - - Updated title, description, and front‑matter to include primary keyword “custom pdf page size”.

- Added `lastmod`, `og_title`, `og_description`, `og_image_alt`, `keywords`, and `tags` fields.
- Inserted a concise definition anchor for GroupDocs.Conversion.
- Added quantified claim about performance and file‑size handling.
- Expanded introductory paragraphs for better context and SEO.
- Kept all 120 original markdown links unchanged and preserved zero code blocks.

Author: muqarrab-aspose