[Feature Request] Docstring/example improvment for theme command

[aikaterna]

Feature request

Complete these first

• [x] I confirm that I have checked the issue tracker and a this feature request doesn't already exist.

Select the type of feature you are requesting:

• [ ] Command
• [x] Functionality

Describe your requested feature

Users don't know how to make their own themes and it's not intuitive. The docstring on the command should be improved with examples and a short explanation.