Update rack_xt_manual.mdx for XT 2.2

XT 2.2 isn't here quite yet but will be soon.

src/content/pages/rack_xt_manual.mdx

@@ -336,6 +336,7 @@ Each of these effects is described in more detail in the [Surge XT manual](../ma
         Can be CPU intensive.
     -   **Delay**: A Digital Delay, strictly monophonic but supports delays up to 10 seconds and includes
         tempo-sync without a block latency delay.
+    -   **Nimbus**: The Surge port of a famous euro-rack granular reverb/delay/spectral manipulator.
 -   Modulation Effects
     -   **Phaser**: A digital phaser with many options to control the filter network
     -   **Flanger**: A flanger with some advanced feedback and tuning options
@@ -347,6 +348,7 @@ Each of these effects is described in more detail in the [Surge XT manual](../ma
     -   **Distortion**: The name kinda gives it away right?
     -   **Neuron**: A saturation circuit
     -   **Chow**: An interesting asymmetric saturator
+    -   **Bonsai**: A broad ranging tape saturation and distortion model.
 -   Special Effects
     -   **Frequency Shifter**: A stereo extendible frequency shifter
     -   **Ring Modulator**: A model of an analog ring modulator, with a multi-shape unison internal carrier
@@ -558,11 +560,11 @@ The module is polyphonic, by default the poly count on the Reset input.
 These modules process modulation input per-block.
 The envelopes respond to triggers in a sample accurate manner though, so no latency there.
 
-# Mixer Modules
+# Mixer and Manipulator Modules
 
 We have two mixer modules. One is intended for audio signals, the other for modulation, though you can do it "wrong" if you like.
 
-## Mixer
+## Mixer and Mixer with Sliders
 
 The Rack Mixer is an implementation of the VST mixer section. It contains
 
@@ -572,8 +574,28 @@ The Rack Mixer is an implementation of the VST mixer section. It contains
 -   Full polyphony and modulation support
 -   Mute and Solo for each channel
 
+There is a version with knobs, and a version with sliders. They do the same thing, just different face plates.
+
 ![Mixer Module](/images/rack-xt-manual/mixer.PNG)
 
+## The Unison Module and Unison CV Expander
+
+The unison module allows non-Surge VCOs to participate in surge unison. It does this by providing 
+a function which converts a polyphonic v/oct signal into an expanded polyphonic v/oct signal, and then
+by collecting and mixing resulting higher-polyphony audio signals into a stereo field. It has an expander
+allowing you to route CV along the same polyphony-expansion path, sports a low and high pass filter, and provides
+drift and character effects from the Surge VCOs.
+
+Patching the module requires some care. The simplest case is taking a monophonic v/oct in, which then generates a
+N-voice polyphonic v/oct out. Patch that to your favorite poly VCO, take the audio output from that VCO back into
+the unison module audio in, and you will get a stereo unison.
+
+As voice count increases you may need extra VCOs. The module supports up to 4 subordinate VCOs, allowing up to 64 
+unison voices, so can add 4-voice unison to 16-way polyphony or up to 9-voice unison with 7 voice polyphony if all the
+VCOs are connected.
+
+To see a demonstration of the unison module just before we shipped 2.2, we prepared this [development preview](https://youtu.be/w0fXLlHKLrk)
+
 ## The Mod Matrix
 
 We think the Surge modulation matrix model is really great! And it would be great