MATLAB Plot Textbox Annotation

I already have a simple MATLAB script that plots a sine wave; now I need the finishing touch. Please update the code so it adds a single textbox annotation, positioned in the top-left corner of the axes, and displays nicely formatted text (no bullet symbols). The original snippet uses LaTeX bullets and a center-placed box—those parts should be replaced.

Deliverable: a clean .m file or code block I can paste straight into MATLAB R2023a, showing the sine plot with the correctly placed, bullet-free textbox. Make sure the annotation respects the usual figure margins and scales properly if the window is resized.