There is no migration tool unfortunately. I did the same process (2008 -> 2016) late last year and below are the notes I made while I was going.
I've replaced my server names with generic names and in my case the old setup had SSRS running on a different server to the database engine so when you see OLD_DB_SERVER_NAME and OLD_SSRS_SERVER_NAME they may actually be the same server in you case.
Hope you find this useful.
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