Add redirect for docs.camunda.io/docs to docs.camunda.io

[akeller]

Kapa AI is using docs.camunda.io/docs as a place to send people in conversations. We've also had issues in the past with people trying to use the URL, but it doesn't resolve. Adding a redirect would be a quick fix here.

[akeller]

FYI @pepopowitz, this might be a practice we want to carry through other areas of our docs.