Meilisearch Cloud update guide

[guimachiavelli]

Updating Meilisearch when using Meilisearch Cloud is a significantly different process than when self-hosting.

A short guide instructing users how to do this and whether there are any pitfalls they may encounter, especially when migrating from older versions, could be helpful.

Could alternatively be an update to the current updating guide, but it might make the document structurally complex.