docs: add changelog entry for versioned docs with mike

Author: amrit110

CHANGELOG.md

@@ -10,6 +10,8 @@ The format is based on Keep a Changelog, and the project follows Semantic Versio
 
 ### Added
 
+- Versioned documentation with a version selector powered by `mike` and MkDocs Material. Each release tag deploys a pinned version; pushes to `main` update a `dev` alias. The `mike`, `mkdocs-material`, and `pymdown-extensions` packages are now included in the `[dev]` optional group.
+
 - `load_export(path)` reader API that loads any export produced by `export_batch(...)` — both combined (single file) and per-item (directory) layouts — and returns a structured `ExportResult`. Failed points are NaN-filled rather than dropped, partial model runs are surfaced via `status="partial"`, and `ExportResult.embedding(model)` provides a typed shortcut to the embedding array.
 
 ### Fixed