Add a docs section to pr template

[EMaksy]

Description

This pr updates the pr template, by adding a docs section.
This change should remind every contributor about updating the documentation. Some parts of the documentation could be used in Trento's official documentation, so it is important that especially the Manual installation guide and Ansible guide is up-to-date.

Sometimes it would make sense to open a separate pr for a docs update, in this case it would not harm to add a reference in the pr description.
If docs do not require an update, a simple no docs update required would be more than enough, similar like what we write in the "How was this tested" section

How was this tested?

No tests needed

[nelsonkopliku]

Hey @EMaksy thanks for this!

I am fine eitherway with the list of links ore just the reminder.
If you wanna keep the list of links maybe we could compact web related links to a generic https://github.com/trento-project/web/blob/main/guides/

[rtorrero]

Thanks @EMaksy! LGTM

[stefanotorresi]

The problem with adding links is that our documentation is a bit scattered at the moment, so there is no single place one should look into. Certainly it's not just the installation docs, so if you decide to keep it you need to make it more generic.

[janvhs]

Just have some minor changes in writing, but that's 100% optional and it LGTM :D

[EMaksy]

Thanks for the feedback!

I refactored the pr a bit and added a Done section, as an inspiration from the uyuni project.

What I liked about it, it adds a clickable task list with progress see Github: About task lists.
It is fully optional, and everybody can delete the template, but it provides a nice visual touch.

[gagandeepb]

Maybe a consideration for later, but would (optionally, perhaps) putting/linking ticket numbers in PRs be interesting?