Move existing project to Pbiviz 3

I have a few custom visual project build under pbiviz 2.5 and I'd like to move them to pbiviz 3.0 for upgrade new features etc.

I was reading this link from MS.  The only link with some description of migrating to pbiviz 3.  However, it is tough to understand this poor documentation and a lot of links on this page shows 'Page Not Found'.

https://microsoft.github.io/PowerBI-visuals/docs/how-to-guide/migrating-to-powerbi-visuals-tools-3-0/

Does anyone have a better tutorial please. thank you.