docs: Remove the MyST migration ADRs

The records served the planning phase of PR #315 and stay in this
branch's history. README.md and content/myst.yml drop their pointers.

Refs #315
Assisted-by: claude-code:claude-fable-5-1 [3M1LY]

Author: lundybernard

README.md

@@ -34,10 +34,3 @@ built with [MyST-MD](https://mystmd.org/) (the `mystmd` CLI).
 serve `content/` only — the cookie overlay is **not** visible there. To preview
 the full site, including `/development/`, use `make build-serve`. It is a static
 build (no live reload); rerun it after edits.
-
-## Decisions
-
-Architecture decisions are recorded in
-[`docs/decisions/`](docs/decisions/). See
-[`0001-myst-migration/`](docs/decisions/0001-myst-migration/) for the
-Hugo → MyST migration.

content/myst.yml

@@ -1,7 +1,6 @@
 version: 1
 # Inherit shared Scientific Python theme (template, footer, plugins, CSS).
-# Vendored from scientific-python/scientific-python-myst-theme via copier;
-# see docs/decisions/0001-myst-migration/0007-myst-theme-integration.md.
+# Vendored from scientific-python/scientific-python-myst-theme via copier.
 extends: config/scientific-python.yml
 
 project: