Create job-board curriculum for begintermediate students

- Add discussion, error, and source_code_with_message methods
- Update docs index
Rename name-collisiony discussion method so that the intermediate curriculum isn't broken
Fix silly name clashing that ruined the intermediate curriculum CSS
Really kill Turbolinks and clean up mistakes

- Fewer syntax errors, more accurate instructions
Typo fixes and add content to placeholders
`error_box` arity is one :boom:
Trivial commit to re-trigger CI build
Small syntax fixes for job board curriculum