Use the term "points" instead of "screen coordinates"

It turns out that screen coordinates were confusing people, thinking that meant pixels, when instead they are virtual coordinates; device independent units defined as pixels scaled by the display scale. We'll use the term "points" for this going forward, to reduce confusion.

docs/README-migration.md

@@ -668,8 +668,8 @@ here, now. Passing NULL is the same as passing -1 here in SDL2, to signify you w
 to decide for you.
 
 When a renderer is created, it will automatically set the logical size to the size of
-the window in screen coordinates. For high DPI displays, this will set up scaling from
-window coordinates to pixels. You can disable this scaling with:
+the window in points. For high DPI displays, this will set up scaling from points to
+pixels. You can disable this scaling with:
 ```c
     SDL_SetRenderLogicalPresentation(renderer, 0, 0, SDL_LOGICAL_PRESENTATION_DISABLED, SDL_SCALEMODE_NEAREST);
 ```