[IMP] accounting: reports groupby non-stored fields

[Megaaaaaa]

In 18.0, this commit added the ability to group by fields that are non stored. This commit adds documentation about how to use the feature.

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task-4698321

[robodoo]

[dade-odoo]

Hi @Megaaaaaa , thanks for your patience on this one as we have a bit of a backlog for accounting/localization documentation reviews. Rather than send a bunch of comments nitpicking on changes, I've made the changes myself, focusing on RST format, avoiding second person (when reasonable), and explaining concepts in written text instead of relying on screenshots, all in an effort to better fit our content guidelines. I've also made changes to other parts of this documentation besides the section that you added. Will you please review my changes to make sure I haven't altered the meaning of any of the explanations and left out anything that was technically necessary? Thanks!

[Megaaaaaa]

Looks good to me. @tsb-odoo, do you want to have one last look ?

[dade-odoo]

Hey @tsb-odoo , do you want to take one last look to check the accuracy of what we have here or should we go ahead with a final review from the doc team and publish?

[Megaaaaaa]

@dade-odoo I think we should merge this as is, all looks good tbh, if something's really problematic, we can always iterate :+1:

[tsb-odoo]

I agree