fix(release): correct docs/license.md symlink to fix crates.io publish failure

[blink-so]

Root cause

• Release job failed at the "Publish to crates.io" step. Cargo packaging errored with:
  failed to open for archiving: docs/license.md -> No such file or directory
  The path existed as a symlink but pointed outside the repository, so Cargo could not resolve it during packaging.

Fix

• Update docs/license.md to point to the repository's LICENSE (../LICENSE) so the file exists and Cargo can include it in the crate package.

Notes

• All CI tests in the release workflow succeeded; only the publish step failed. This change is limited to fixing the broken symlink used during packaging.
• After merge, tag a new release (e.g., v0.4.2) so the release workflow runs against a commit that contains this fix. Re-running the v0.4.1 workflow will still use the old tag and fail.

Testing

• Verified the symlink now resolves within the repo tree; CI will validate via the release workflow.