Chapter Two: translate to Spanish

- [ ] Fork repo
- [ ] Review build system (not necessary to do PDF, HTML is sufficient to check on translation formatting
- [ ] Create working branch
- [ ] Work in `/manuscripts/es/...` and output to `/_preview/en/...`
- [ ] Push ongoing work to your own forked repo working branch
- [ ] When ready, perform pull request to this repo from your pushed working branch.