[V3] docs: added info about $wire.set() defer

[lukas-frey]

Review the contribution guide first at: https://laravel-livewire.com/docs/2.x/contribution-guide

1️⃣ Is this something that is wanted/needed? Did you create a discussion about it first?

2️⃣ Did you create a branch for your fix/feature? (Master branch PR's will be closed)

3️⃣ Does it contain multiple, unrelated changes? Please separate the PRs out.

4️⃣ Does it include tests? (Required)

5️⃣ Please include a thorough description (including small code snippets if possible) of the improvement and reasons why it's useful.

Thanks for contributing! 🙌

[calebporzio]

Perfect, thanks!