[2018] The new ailments are Scorched, Brittle, and Sapped

We didn't change the tree specifically, we changed the reminder text on things that refer to "ailments" and then explain what things that means, because that has changed. How easy that thing is to get doesn't matter, it is an ailment, so the explaination of what things are ailments needs to include it so it's not lying to the player.

Can you find the mechanics details of ignite, chill/freeze, and shocked in the game?

These all have reminder text - any stat which causes them or has a chance to cause them will have reminder text attached (can be viewed by holding alt) explaining the basics of how they work.

The "main" 4 elemental ones can be caused on crit (on hit for chill) without any stats, so it's possible to be inflicting them without having an item that includes that explaination, but I believe those ones are specifically covered by the in-game help panel as well.

The new ailments are the same - if you can inflict Scorched, then the same stat that lets you do that also has the reminder text that explains what Scorched does.