Update ansi.md

[sholderbach]

To test the manual update warner

[github-actions]

Awesome that you are trying to improve the documentation of a nushell command!

As we autogenerate these command pages from the help information defined with the command after each release:

• If you already updated the command help, you are already done!
• Else, please look for the command in the source tree and make your changes directly there.

Thanks for helping out!