Add dynamic IOQ class documentation
diff --git a/IOQ2.md b/IOQ2.md
index ddf8d22..849fbe2 100644
--- a/IOQ2.md
+++ b/IOQ2.md
@@ -611,6 +611,16 @@
```
+### Dynamic IOQ classes
+
+To support 3rd party IO channels for things like search/geo/cache/etc, you can
+manually set a config priority for the desired class, and then it will be
+picked up by `ioq_config:is_valid_class/1`. Because the `ioq_config:set_*`
+setters depend on `is_valid_class`, you must manually define the priority
+initially, for example with `config:set("ioq.classes", "search", "1.0").`.
+Afterwards, you'll be able to utilize the setters as expected.
+
+
## ioq_server2:get_state
You can see a human readable representation of the IOQ2 server state with the
