Design a technote deprecation process, engineer it, and document it.
The process was sketched for DMTN-026:
1. In metadata.yaml add these fields:
2. At the top of your index.rst, but below the :tocdepth: 1, including a warning directive:
- Make it so that only (1) or (2) are needed to officially deprecate a technote.
- Add a `canonical-url` header into deprecated technotes pointing to a replacement link so that Google will prefer the replacement URL over offering a deprecated document.