Add reference docs for CLI example functionality

[alex-zenml]

Pre-requisites

Please ensure you have done the following:

• I have read the CONTRIBUTING.md document.
• If my change requires a change to the documentation, I have updated the documentation accordingly.
• I have added tests to cover my changes.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Describe changes

Added a section relating to the zenml example commands in the CLI reference docs
Added a todo in src relating to a bug I found in the example command functionality (relates to what happens when you do a new release).

[htahir1]

Cool! As a note I also put some of this information here: https://github.com/zenml-io/zenml/tree/main/examples