Improve karls-picture.typ

[yerlotic]

• Fix spelling mistakes in comments
• Make angle into a variable
• Fix rendering for angles > 90 degrees

[johannes-wolf]

Thank you for this PR, but it does not fix angles > 90°. You can use (angle, 1) for polar coordinates instead of (cos(angle), sin(angle)) btw. You are right, the example needs some cleanup and fixes.

[yerlotic]

So I changed some things in bd31aaf

• Added corner rounding to math elements on top of a graph
• Changed the angle to 212°
• Added a label to the angle
• Changed stroke: (paint: sth) to stroke: sth
• Added a secondary grid (and it would be cool to strip the borders from the grid from all 4 sides, but idk how to do it)

Feel free to undo any of the changes you find unnecessary

This is how it looks like now:

[johannes-wolf]

Pushed this branch + changes on #1120.