[8.x] Add Meilisearch upgrade note to Scout docs

[driesvints]

Adding this note will inform users to review Meilisearch breaking changes when they update their Meilisearch binary.

This also contains a note about compatibility between meilisearch-php and the meilisearch binary.

See laravel/scout#516

[georgeboot]

Perhaps we should also include something about compatibility between the meilisearch-php and the server? For example, composer installs latest meilisearch-php but brew install meilisearch on MacOS will install 0.20.0, which will now break.

[driesvints]

Isn't scout now compatible with all Meilisearch versions? I thought your PR with the version check did just that.

[georgeboot]

The whole thing is that if you have meilisearch server 0.21 and meilisearch-php 0.19, you are fine. Scout handles that. This is also the correct setup.

However, a (new) user might simple install the latest versions of everything. This will mostly go correct, but for example on Homebrew, 0.21 isn't available, and now you are getting a super strange error.

Users need to install the correct sdk version for the server version they have.

Probably super niche, so not worth a note in the docs, but felt I should at least share so you can make a decision on it.

[driesvints]

@georgeboot that's a good remark, thanks for noting that. Can you maybe send in a PR to my PR for a proposal? Or just comment here how you'd note it?

[georgeboot]

I would add the following in the docs under the driver prerequisites section, directly under the composer install for meili:

Make sure you install a version of meilisearch/meilisearch-php that is compatible with your server version. You can check compatibility here.

[driesvints]

Thanks @georgeboot. I added that albeit a bit lower.