Document gotcha with :is and DOM props

[ferk6a]

This is #2241 reborn. The motivation for it is that this snippet of code:

<component :is="multiline ? 'textarea' : 'input'" v-model="value">

Won't work as would expect, so we are documenting that you should, instead, use :value.prop and @input instead of v-model.

[phanan]

Pinging @sdras as she's been involved with the other from day 1.

[sdras]

perfect, thank you for resubmitting!

[vue-bot]

Thanks again! 💚

[ferk6a]

No problem!