Better document cli commands
Syntax and spacing tweaks
Remove unnecessary indentation in demos
Better self documentation of the cli
Slightly improve cli documentation with relevant commands
Restore demo config documentation
Change wording of 'run' to 'preview'
Improve messaging around old demo format
Fix demo messaging
Precise where to paste the demo config
Update README.md
Merge pull request #148 from Financial-Times/improve-cli-documentation

Improve cli documentation