Add descriptions to tasks

[roaldarbol]

Problem description

Suggestion is two-fold: 1) Adding a "description" field for tasks, and 2) echoing those descriptions on pixi task list.

Quite a lot of use-cases, there's for future others: if you have colleagues that need to use your project, it might be useful to have those descriptions. For current self: for oneself to remember what each task does without leaving the command line). And of course for future self: when returning to those commands at a later stage, it would be a nice reminder what they are for - just as annotating code is.

[ruben-arts]

I like the idea, design wise I would also print it in pixi run where pixi already prints the command itself.

[roaldarbol]

Yeah, that would be great too!

[ruben-arts]

Closed as implemented in #1479