ADR ACTIONS_RUNNER_CONTAINER_HOOKS name fix

**Describe the bug**
[ADR](https://github.com/actions/runner/blob/0d1e6fd57bc798e14876593ad9aa0e4cb6e5e676/docs/adrs/1891-container-hooks.md?plain=1#L19)  states that the env variable is `ACTIONS_RUNNER_CONTAINER_HOOK`, but it should be `ACTIONS_RUNNER_CONTAINER_HOOKS`
