[ Fix ] Incorrect cropper library used in readme

[kostamilorava]

In readme.md, there is incorrectly linked cropper library. Instead of vuejs-clipper it should be advanced-cropper.

Other than that, only stencil-props configuration is passed, leaving other needed properties like: minWidth, minHeight of cropper area and others aside.

Maybe it's a good idea to pass other configurations as well and override src property (and other needed props) on Vue.js side? This will make sure whole functionality of cropper is available.

Let's merge this pull request and let me know if you think it's a good idea, I might implement solution for this.