`npm run docsgen` writes bad URLs in README

The per-command GitHub file URLs that `npm run docsgen` generates inside `/README.md` are inherently flawed and will always 404.

Example:
```markdown
_See code: [src/commands/collection/delete.ts](https://github.com/itopia-inc/spaces-cli/blob/v0.1.0/src/commands/collection/delete.ts)_
```

This is because most command files are not currently versioned.