reworked vectorscopes documentation for new split view

[anoderay]

updates scopes documentation to match pr 20740 with new screenshots and wording.

[Phemisters]

To avoid confusion, can you confirm this PR means that the existing #839 can be closed (since they address the same area, but yours is presumably more up-to-date)?

[anoderay]

To avoid confusion, can you confirm this PR means that the existing #839 can be closed (since they address the same area, but yours is presumably more up-to-date)?

I am an idiot, sorry. I didn't properly look whether the work had already been done. I am just getting started working on the docs. Your Screenshots are prettier.

[Phemisters]

I am an idiot, sorry. I didn't properly look whether the work had already been done. I am just getting started working on the docs. Your Screenshots are prettier.

It's not a problem - it is always good to have contributions to the docs. I'll be looking at your changes to make sure everything gets covered.

For the screen shots, one difference between them is the size of some icons - to make the icons and text bigger (which makes the screenshots work better on a variety of displays) I usually temporarily alter the darktable GUI controls and text DPI (and sometimes the font size in pixels) in the preferences/general tab.