documentation & rotation

[hhansen06]

• added documentation for drawcustom to readme
• added rotation functionality on draw

[jonasniesner]

Why was this PR closed?

[hhansen06]

i broke something. should now be fixed.

[jonasniesner]

Thank you, merged. The preview image maybe could be a good use of the Image entity(https://developers.home-assistant.io/docs/core/entity/image/).