Added circle command but i have questions.

[NiclasTheSquirrel]

I have added the circle command, but this is my first time contributing to something on github, so please if you see that i have done something wrong, done something in a diffrent way than i should have, change it and let me know. I dont know if i should use ellipseMode(center) or not, or if i should use w,h instead of radius.

[TheTastefulToastie]

Thank you for contributing ❤️
Don't worry about 'making mistakes' Git and Github makes it easy to change things afterwards, just go for it.

I couldn't find a circle command in the Berkeley Logo Manual but there is an ARK command:

ARC angle radius

	draws an arc of a circle, with the turtle at the center, with the
	specified radius, starting at the turtle's heading and extending
	clockwise through the specified angle.  The turtle does not move.

As the ARC command takes a radius parameter it will be measures from the center as opposed to a corner.