docs: decline documentation and skill translations

State in CONTRIBUTING.md that translations of docs and skills are not
accepted: translated copies drift as content evolves and can't be
maintained long-term without leaning on agent translations plus
community corrections, for limited value.

CONTRIBUTING.md

@@ -68,6 +68,10 @@ The frontmatter fields above are required. The section anatomy is a recommended
 
 `AGENTS.md` and `CLAUDE.md` at the repo root configure agents working on the [`addyosmani/agent-skills`](https://github.com/addyosmani/agent-skills) repository itself. When writing setup guides or docs, do not instruct users to copy these files into their own projects or into a global agent configuration; the reusable assets are the skills in `skills/`.
 
+## Translations
+
+We don't accept translations of the documentation (README, `docs/`) or of skills and their content. Translated copies drift out of sync as skills and docs evolve, and we have no way to maintain them long-term without leaning on agent translations plus community corrections, which adds maintenance cost for limited value. Keep all skills, docs, and contributions in English.
+
 ## Testing Hooks
 
 The session-start hook (`hooks/session-start.sh`) injects the `using-agent-skills` meta-skill into every new Claude Code session. A regression test at `hooks/session-start-test.sh` validates the hook's JSON payload — both when `jq` is available and when it isn't.