Document how to hide Talon HUD from captures.

README.md

@@ -15,6 +15,10 @@ installed as a sibling in the same directory.
 Beta, switch to the "beta" branch (add flag `-b beta`) to take advantage of
 beta-only features. 
 
+If you use [Talon HUD](https://github.com/chaosparrot/talon_hud), consider
+setting `user.talon_hud_allows_capture = 0` to make the HUD invisible to OCR
+(only supported on Talon Beta).
+
 Required permissions:
 
 - On Mac, Talon requires the ability to read the screen. As per the