docs: add 0.1.6 release notes (#17)

Author: lesnik512

planning/releases/0.1.6.md

@@ -0,0 +1,28 @@
+# compose2pod 0.1.6 — accept the service `tmpfs` key
+
+A patch release that stops rejecting valid compose documents which set a
+service `tmpfs`. The validator was over-strict: a service carrying `tmpfs:` —
+a string or list of `<path>[:<options>]` entries, e.g. `/tmp:mode=1777` —
+raised `unsupported key 'tmpfs'`. Such documents now convert.
+
+## Fix
+
+- **The service `tmpfs` key is accepted.** `validate()` no longer rejects a
+  service that sets `tmpfs:`. Each entry is emitted verbatim as `podman run
+  --tmpfs <value>` — Compose's short syntax maps directly onto podman's own
+  `--tmpfs CONTAINER-DIR[:OPTIONS]` flag, so no translation is needed. No
+  format validation; a malformed option string surfaces as a podman error at
+  run time.
+
+## Downstream
+
+No action needed — additive and backward compatible. Documents that previously
+failed with `unsupported key 'tmpfs'` now emit a pod script; nothing that
+converted before changes.
+
+## Internals
+
+- `architecture/supported-subset.md` documents `tmpfs` in the Service keys
+  matrix.
+- 98 tests at 100% line coverage (enforced); `ruff select=ALL`, `ty`, and
+  `eof-fixer` clean.