Update lib documentation

**Description**
Currently routes lacks proper backup support.

**Proposed solution**
Add configurable backup with sensible defaults.

**Priority**: Low/Medium

Start by reading the lib documentation and tracing the routes entry point to determine how backup is currently handled. Clarify the configurable options and sensible defaults before changing behavior; done means routes support the agreed backup configuration and existing behavior remains covered by the relevant tests.

Written by the indexing model from the issue text.