Article BYOA migrate and update

[FloorD]

I would like to see a page dedicated to Bring Your Own Account (BYOA) instructions on the Developer Portal.

Currently there's an article on help.aiven.io: https://help.aiven.io/en/articles/2353018-bring-your-own-account-byoa-model ... and a blog post: https://aiven.io/blog/bring-your-own-account-to-aiven

I want to test the steps and create a new article, under Platform > How to

Is this something you would work on yourself?

[x] I plan to open a pull request for this