Enhance Dynamic Variables documentation with examples

I think the Dynamic Variables section could be enhanced by providing examples of how to create a new "Bruno" variable from a random one and including a link to https://docs.usebruno.com/variables/runtime-variables.

I struggled to find information on how to create or modify a "Bruno" variable from a random date. The ISO8601 date format was not the one expected by the API, so I couldn't use the dynamic variable directly in the body with {{$randomDatePast}}.

Should I create a pull request to update src/pages/testing/script/dynamic-variables.mdx?

[ganesh-bruno]

Hi, @hugo-thiessard-digimobee

Feel free to open a pull request. We’d appreciate your contribution.

[ganesh-bruno]

Hi, @hugo-thiessard-digimobee

Quick check: did you get any chance to submit PR on changes you're suggesting above?