chore: modify option key namespaces => ns

[anc95]

Checklist

• [x] only relevant code is changed (make a diff before you submit the PR)
• [x] run tests npm run test
• [x] tests are included
• [x] documentation is changed or added

hello due to the doc at https://www.i18next.com/overview/configuration-options#languages-namespaces-resources

the option key should be ns instead of namespaces

[jamuhl]

Uh...good catch...a very bad mistake on my side...thanks for taking the time to provide the correction. 🙏