doc: document how to install and use Task in a Go module as a tool

[dolmen]

Description

As Task is written in Go, it can be installed in a Go module as a tool since Go 1.24:

$ go get github.com/go-task/task/v3/cmd/task@latest

Then that specific version locked in the go.mod can be called via go tool task:

$ go tool task --list

In the installation manual this specific install method for Go module should be documented. In particular, this should be the privileged way to install and use Task in CI for Go projects.

[andreynering]

Hi @dolmen,

Yep, this feature is indeed really cool, and I've used it for other tools.

This is also a cool idea for a blog post.