Enhancement: Update readme for Vue3 usage

[verena-ifx]

Using Vue3 with Vite led to some warnings. This can be solved by setting a compiler option in vite.config.js
Update readme information accordingly:

plugins: [
vue({
template: {
compilerOptions: {
// treat all tags with a dash as custom elements
isCustomElement: (tag) => tag.includes('ifx-'),
},
},
}),
],

[tishoyanchev]

Updated in another Issue: #1234