Update Mod list

Mod-list.md

@@ -58,6 +58,10 @@ The rating is client-side and purely cosmetic. The profile option is stored on t
 
 ## UnlockFrameRate
 
+The name is historical; it can also lock the framerate at an arbitary value, and fixes the game on HFR monitors.
+
+### Settings
+
 Values are pulled from `mu3.ini`. Example:
 ```ini
 [Video]
@@ -66,10 +70,20 @@ VSync=0
 ```
 Default: `Framerate=60`, `VSync=0`. 
 
-`Framerate=0` to unlock the framerate.
+Set `Framerate=0` to unlock the framerate.
 
 `VSync=1` overrides `Framerate`.
 
+### Details
+
+Normally, the game runs with a framerate lock corresponding to the refresh rate of your monitor primary monitor. This would be awesome if not for two issues: 
+* You may want to run the game on a secondary monitor with `-monitor 2`, and their refresh rates may differ.
+* Although there are no technical obstacles to running the game at HFR, there is a note smoothing/snapping algorithm (refer to `MU3.Notes.NotesManager.progressFrameAndFrameReal()` that expects the game to run at 60fps, and ties the game's speed to the framerate.
+
+This means that an unmodded setup with a 120Hz primary monitor and a secondary 60Hz ongeki monitor will run the game at double speed, even though the user intended to run at the "proper" framerate.
+
+So, by default, this mod sets the framerate to 60fps always. Optionally, you can lock it to any other value/unlock it/enable vsync, in which case the aforementioned frame snapping gets disabled.
+
 ## SkipPreMusicRitual
 
 By default, it's triggered with the red menu button, but you can make it permanent by adding this to `mu3.ini`: