fix(docs): commit redis-logo-script-red.svg referenced by index.md (#32)

The hero block on the docs landing page (added in #31) references
`assets/redis-logo-script-red.svg` (the cursive Redis wordmark in the
official red #FF4438), but the file itself was never committed. The
GitHub Pages build runs with `mkdocs build --strict`, which promotes
the resulting warning into a hard failure:

  WARNING -  Doc file 'index.md' contains a link
             'assets/redis-logo-script-red.svg', but the target is not
             found among documentation files.
  Aborted with 1 warnings in strict mode!

Add the missing asset alongside the existing white-fill variant
(`redis-logo-script.svg`, used in the dark navbar). Verified locally:

  $ DISABLE_MKDOCS_2_WARNING=true uv run --group docs mkdocs build --strict
  INFO    -  Documentation built in ~3s

Author: nkanu17