Update redirects to reflect new permanent default

- Remove all 'permanent: true' entries from docs.yml as it's now the default
- Update redirect documentation to specify default is now true (308 permanent)
- Update parameter descriptions to match user requirements:
  - source: incoming request path pattern
  - destination: path you want to route to
  - permanent: true by default, uses 308 (permanent/cached) or 307 (temporary/not cached)
- Add example of temporary redirect with permanent: false

Related to fern-api/fern-platform#4141

Co-Authored-By: [email protected] <[email protected]>

Author: devin-ai-integration[bot]