[Docs] Add note about using Unicode Hex Input (#5248)

* Add note about using Unicode Hex Input

* Update docs

* remove extra return, oops

docs/feature_unicode.md

@@ -65,6 +65,8 @@ The following input modes are available:
   To enable, go to _System Preferences > Keyboard > Input Sources_, add _Unicode Hex Input_ to the list (it's under _Other_), then activate it from the input dropdown in the Menu Bar.
   By default, this mode uses the left Option key (`KC_LALT`), but this can be changed by defining [`UNICODE_OSX_KEY`](#input-key-configuration) with another keycode.
 
+  **Note:** Using the _Unicode Hex Input_ input source may disable some Option based shortcuts, such as: Option + Left Arrow (`moveWordLeftAndModifySelection`) and Option + Right Arrow  (`moveWordRightAndModifySelection`).
+
 * **`UC_LNX`**: Linux built-in IBus Unicode input. Supports code points up to `0x10FFFF` (all possible code points).
 
   Enabled by default and works almost anywhere on IBus-enabled distros. Without IBus, this mode works under GTK apps, but rarely anywhere else.