It is a one of the more obscure places to tuck it away. 
The replacement ones are back in the plugin setup area so you should see those next time you bump up a version (as soon as a couple of weeks or so 
)
The guide still has the older instructions in, if you’d like to give that a once-over to see if it all sounds familiar - Discourse AI - Summarization
There was a ‘50 post minimum’ at one point, but I can’t remember how far back that was changed? It could still be part of stable. Do you have a topic with 50+ posts in you could check?