Improve docs on how ParallaxLayer mirroring works.

[lvella]

I wrote everything I wish was written when I tried to make an infinite scrolling background, addressing every point of every mistake I made.

[AThousandShips]

As expressed on your original PR this feels too big to fit in this section, and belongs in a tutorial in my opinion

[lvella]

Thanks for reviewing.

As expressed on your original PR this feels too big to fit in this section, and belongs in a tutorial in my opinion

I believe the reference docs should be the complete and authoritative source of information. I.e. an official tutorial should bring no more information than what you can piece together from the references.

Of all I wrote, I think only this paragraph doesn't bring novel information important to the motion_mirroring property. It is more like an usage tip:

Notice that if you want the repeatition to pixel-perfect match a [Texture2D] displayed by a child node, you should account for any scale applied to the texture when defining this interval. E.g., if you use a child [Sprite2D] scaled to [code]0.5[/code] to display a 600x600 texture, and want this sprite to be repeated continuously horizontally, you should set the mirroring to [code]Vector2(300, 0)[/code].

But even then, I don't think such an usage tip is out of place in a reference documentation: the reference should be more complete and thorough on the details than a tutorial, not less.

[AThousandShips]

Some style and grammar pointers

Unsure about the verbosity but some good pointers, I think some of the details might be best served in a detailed tutorial explaining things with examples, but works here as well

[lvella]

Sorry for the long delay. I applied all the fixes, thanks.

[lvella]

typo

[lvella]

How can CI fail in building C++ code if I didn't touch it?

[Mickeon]

Neat details to a class that may have desperately needed some, although perhaps it's a little too much. I have reviewed this just when a new Parallax2D node is being in the works so this may be a bit obsolete, but it is nice nonetheless.

[akien-mga]

Committed @Mickeon's suggestions and squashed the commits.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉

[akien-mga]

Cherry-picked for 4.2.2.
Cherry-picked for 4.1.4.