fix: broken link to sample app in README

[S-ecki]

:scroll: Description

A link in the README of the feedback package was broken, linking to a non-existent GitHub page (see screenshot below).

The link was: https://github.com/ueman/feedback/blob/master/example/lib/main.dart And the correct one would be: https://github.com/ueman/feedback/blob/master/feedback/example/lib/main.dart

:bulb: Motivation and Context

Position of broken link on page

Result when clicking link

:green_heart: How did you test it?

Manually

:pencil: Checklist

• [x] I reviewed submitted code
• [ ] I added tests to verify changes
• [ ] I updated the docs if needed
• [ ] All tests passing
• [x] No breaking changes

:crystal_ball: Next steps

[ueman]

Thanks!