docs: show conversion from duration to seconds

[cbandy]

Description

I use Go templates to produce machine-readable files, and one of the challenges I face is producing amounts of time as seconds and milliseconds. I want to write values like "5 minutes" or "30 seconds" for the benefit of file maintainers and have a computer do the math to turn them into numbers.

The toDuration function satisfies my use case and seems valuable to show in the documentation.

Changes

One more example for the toDuration function.

Fixes

Checklist

• I have read the CONTRIBUTING.md document.
• My code follows the code style of this project.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have updated the documentation accordingly.
• This change requires a change to the documentation on the website.

Additional Information

This example matches this test:

sprout/conversion_functions_test.go

Line 130 in aca5c32

{"TestCallingOnIt", `{{ (toDuration "1h30m").Seconds }}`, "5400", nil},

[42atomys]

Hi @cbandy, thanks for your contribution 🎉 💜

Sorry for the delay, I'm in vacation since 2 weeks