Update some v5 migration and Plugin SDK docs

[alexandrebodin]

What does it do?

Updates documentation for v5 topics around migration & plugins

Why is it needed?

v5 is coming :octocat:

Related issue(s)/PR(s)

Let us know if this is related to any issue/pull request

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Name	Status	Preview	Comments	Updated (UTC)
documentation	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 12, 2024 2:29pm

[alexandrebodin]

@pwizla go ahead and merge this with your updates. I'll make another PR for the migration